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  • Is there a better loop I could write to reduce database queries?

    - by dmanexe
    Below is some code I've written that is effective, but makes too many database queries. Is there a way I could optimize and reduce the number of queries but have conditional statements still be as effective as below? I pasted the code repeated a few times just for good measure. echo "<h3>Pool Packages</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Pool Packages") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Pool Packages") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Water Features</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Water Features") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Water Features") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Waterfall Rock Work</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE) { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Waterfall Rock Work") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Sheer Descents</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Sheer Descents") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Sheer Descents") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Booster Pump</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Booster Pump") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Booster Pump") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Pool Concrete Decking</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Pool Concrete Decking") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Pool Concrete Decking") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Solar Heating</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Solar Heating") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Solar Heating") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Raised Bond Beam</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Raised Bond Beam") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Raised Bond Beam") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { echo "<li>None</li>"; } endforeach; echo "</ul>"; It goes on beyond this to several more categories, but I don't know how to handle looping through this best. Thanks!

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  • Why is MySQL table_cache full but never used

    - by Jeremy Clarke
    I have been using the tuning-primer.sh script to tune my my.cnf settings. I have most things working well but the part about TABLE CACHE makes no sense: TABLE CACHE Current table_cache value = 900 tables. You have a total of 0 tables You have 900 open tables. Current table_cache hit rate is 1% , while 100% of your table cache is in use. You should probably increase your table_cache When I do SHOW STATUS; I get the following table-related numbers: Open_tables = 900 Opened_tables = 0 It seems like something is going wrong. I have some extra memory I could use on increasing the table_cache size, but my sense is that the 900 tables already available aren't doing anything, and increasing it will just waste more energy. Why might this be happening? Are there other settings that could cause all my table_cache slots to be used even though there are no hits to them? I have 150 max connections and probably no more than 4 tables per join, FWIW. Here is the tuner script output for temp tables, which I've also been tuning: TEMP TABLES Current max_heap_table_size = 90 M Current tmp_table_size = 90 M Of 11032358 temp tables, 40% were created on disk Perhaps you should increase your tmp_table_size and/or max_heap_table_size to reduce the number of disk-based temporary tables. Note! BLOB and TEXT columns are not allow in memory tables. If you are using these columns raising these values might not impact your ratio of on disk temp tables.

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  • SQL SERVER – Disable Clustered Index and Data Insert

    - by pinaldave
    Earlier today I received following email. “Dear Pinal, [Removed unrelated content] We looked at your script and found out that in your script of disabling indexes, you have only included non-clustered index during the bulk insert and missed to disabled all the clustered index. Our DBA[name removed] has changed your script a bit and included all the clustered indexes. Since our application is not working. When DBA [name removed] tried to enable clustered indexes again he is facing error incorrect syntax error. We are in deep problem [word replaced] [Removed Identity of organization and few unrelated stuff ]“ I have replied to my client and helped them fixed the problem. What really came to my attention is the concept of disabling clustered index. Let us try to learn a lesson from this experience. In this case, there was no need to disable clustered index at all. I had done necessary work when I was called in to work on tuning project. I had removed unused indexes, created few optimal indexes and wrote a script to disable few selected high cost indexes when bulk insert (and similar) operations are performed. There was another script which rebuild all the indexes as well. The solution worked till they included clustered index in disabling the script. Clustered indexes are in fact original table (or heap) physically ordered (any more things – not scope of this article) according to one or more keys(columns). When clustered index is disabled data rows of the disabled clustered index cannot be accessed. This means there will be no insert possible. When non clustered indexes are disabled all the data related to physically deleted but the definition of the index is kept in the system. Due to the same reason even reorganization of the index is not possible till the clustered index (which was disabled) is rebuild. Now let us come to the second part of the question, regarding receiving the error when clustered index is ‘enabled’. This is very common question I receive on the blog. (The following statement is written keeping the syntax of T-SQL in mind) Clustered indexes can be disabled but can not be enabled, they have to rebuild. It is intuitive to think that something which we have ‘disabled’ can be ‘enabled’ but the syntax for the same is ‘rebuild’. This issue has been explained here: SQL SERVER – How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’. Let us go over this example where inserting the data is not possible when clustered index is disabled. USE AdventureWorks GO -- Create Table CREATE TABLE [dbo].[TableName]( [ID] [int] NOT NULL, [FirstCol] [varchar](50) NULL, CONSTRAINT [PK_TableName] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO -- Create Nonclustered Index CREATE UNIQUE NONCLUSTERED INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] ([FirstCol] ASC) GO -- Populate Table INSERT INTO [dbo].[TableName] SELECT 1, 'First' UNION ALL SELECT 2, 'Second' UNION ALL SELECT 3, 'Third' GO -- Disable Nonclustered Index ALTER INDEX [IX_NonClustered_TableName] ON [dbo].[TableName] DISABLE GO -- Insert Data should work fine INSERT INTO [dbo].[TableName] SELECT 4, 'Fourth' UNION ALL SELECT 5, 'Fifth' GO -- Disable Clustered Index ALTER INDEX [PK_TableName] ON [dbo].[TableName] DISABLE GO -- Insert Data will fail INSERT INTO [dbo].[TableName] SELECT 6, 'Sixth' UNION ALL SELECT 7, 'Seventh' GO /* Error: Msg 8655, Level 16, State 1, Line 1 The query processor is unable to produce a plan because the index 'PK_TableName' on table or view 'TableName' is disabled. */ -- Reorganizing Index will also throw an error ALTER INDEX [PK_TableName] ON [dbo].[TableName] REORGANIZE GO /* Error: Msg 1973, Level 16, State 1, Line 1 Cannot perform the specified operation on disabled index 'PK_TableName' on table 'dbo.TableName'. */ -- Rebuliding should work fine ALTER INDEX [PK_TableName] ON [dbo].[TableName] REBUILD GO -- Insert Data should work fine INSERT INTO [dbo].[TableName] SELECT 6, 'Sixth' UNION ALL SELECT 7, 'Seventh' GO -- Clean Up DROP TABLE [dbo].[TableName] GO I hope this example is clear enough. There were few additional posts I had written years ago, I am listing them here. SQL SERVER – Enable and Disable Index Non Clustered Indexes Using T-SQL SQL SERVER – Enabling Clustered and Non-Clustered Indexes – Interesting Fact Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Constraint and Keys, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Server Side Paging in SQL Server 2011 Performance Comparison

    - by pinaldave
    Earlier, I have written about SQL SERVER – Server Side Paging in SQL Server 2011 – A Better Alternative. I got many emails asking for performance analysis of paging. Here is the quick analysis of it. The real challenge of paging is all the unnecessary IO reads from the database. Network traffic was one of the reasons why paging has become a very expensive operation. I have seen many legacy applications where a complete resultset is brought back to the application and paging has been done. As what you have read earlier, SQL Server 2011 offers a better alternative to an age-old solution. This article has been divided into two parts: Test 1: Performance Comparison of the Two Different Pages on SQL Server 2011 Method In this test, we will analyze the performance of the two different pages where one is at the beginning of the table and the other one is at its end. Test 2: Performance Comparison of the Two Different Pages Using CTE (Earlier Solution from SQL Server 2005/2008) and the New Method of SQL Server 2011 We will explore this in the next article. This article will tackle test 1 first. Test 1: Retrieving Page from two different locations of the table. Run the following T-SQL Script and compare the performance. SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO You will notice that when we are reading the page from the beginning of the table, the database pages read are much lower than when the page is read from the end of the table. This is very interesting as when the the OFFSET changes, PAGE IO is increased or decreased. In the normal case of the search engine, people usually read it from the first few pages, which means that IO will be increased as we go further in the higher parts of navigation. I am really impressed because using the new method of SQL Server 2011,  PAGE IO will be much lower when the first few pages are searched in the navigation. Test 2: Retrieving Page from two different locations of the table and comparing to earlier versions. In this test, we will compare the queries of the Test 1 with the earlier solution via Common Table Expression (CTE) which we utilized in SQL Server 2005 and SQL Server 2008. Test 2 A : Page early in the table -- Test with pages early in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 5 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO Test 2 B : Page later in the table -- Test with pages later in table USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 ;WITH CTE_SalesOrderDetail AS ( SELECT *, ROW_NUMBER() OVER( ORDER BY SalesOrderDetailID) AS RowNumber FROM Sales.SalesOrderDetail PC) SELECT * FROM CTE_SalesOrderDetail WHERE RowNumber >= @PageNumber*@RowsPerPage+1 AND RowNumber <= (@PageNumber+1)*@RowsPerPage ORDER BY SalesOrderDetailID GO SET STATISTICS IO ON; USE AdventureWorks2008R2 GO DECLARE @RowsPerPage INT = 10, @PageNumber INT = 12100 SELECT * FROM Sales.SalesOrderDetail ORDER BY SalesOrderDetailID OFFSET @PageNumber*@RowsPerPage ROWS FETCH NEXT 10 ROWS ONLY GO From the resultset, it is very clear that in the earlier case, the pages read in the solution are always much higher than the new technique introduced in SQL Server 2011 even if we don’t retrieve all the data to the screen. If you carefully look at both the comparisons, the PAGE IO is much lesser in the case of the new technique introduced in SQL Server 2011 when we read the page from the beginning of the table and when we read it from the end. I consider this as a big improvement as paging is one of the most used features for the most part of the application. The solution introduced in SQL Server 2011 is very elegant because it also improves the performance of the query and, at large, the database. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Speaking Sessions at TechEd India – 3 Sessions – 1 Panel Discussion

    - by pinaldave
    Microsoft Tech-Ed India 2010 is considered as the major Technology event of the year for various IT professionals and developers. This event will feature a comprehensive forum in order   to learn, connect, explore, and evolve the current technologies we have today. I would recommend this event to you since here you will learn about today’s cutting-edge trends, thereby enhancing your work profile and getting ahead of the rest. But, the most important benefit of all might be the networking opportunity that that you can attain by attending the forum. You can build personal connections with various Microsoft experts and peers that will last even far beyond this event! It also feels good to let you know that I will be speaking at this year’s event! So, here are the sessions that await you in this mega-forum. Session 1: True Lies of SQL Server – SQL Myth Buster Date: April 12, 2010  Time: 11:15pm – 11:45pm In this 30-minute demo session, I am going to briefly demonstrate few SQL Server Myth and their resolution backing up with some demo. This demo session is a must-attend for all developers and administrators who would come to the event. This is going to be a very quick yet  fun session. Session 2: Master Data Services in Microsoft SQL Server 2008 R2 Date: April 12, 2010  Time: 2:30pm-3:30pm SQL Server Master Data Services will ship with SQL Server 2008 R2 and will improve Microsoft’s platform appeal. This session provides an in depth demonstration of MDS features and highlights important usage scenarios. Master Data Services enables consistent decision making by allowing you to create, manage and propagate changes from single master view of your business entities. Also with MDS – Master Data-hub which is the vital component helps ensure reporting consistency across systems and deliver faster more accurate results across the enterprise. We will talk about establishing the basis for a centralized approach to defining, deploying, and managing master data in the enterprise. Session 3: Developing with SQL Server Spatial and Deep Dive into Spatial Indexing Date: April 14, 2010 Time: 5:00pm-6:00pm Microsoft SQL Server 2008 delivers new spatial data types that enable you to consume, use, and extend location-based data through spatial-enabled applications. Attend this session to learn how to use spatial functionality in next version of SQL Server to build and optimize spatial queries. This session outlines the new geography data type to store geodetic spatial data and perform operations on it, use the new geometry data type to store planar spatial data and perform operations on it, take advantage of new spatial indexes for high performance queries, use the new spatial results tab to quickly and easily view spatial query results directly from within Management Studio, extend spatial data capabilities by building or integrating location-enabled applications through support for spatial standards and specifications and much more. Panel Discussion: Harness the power of Web – SEO and Technical Blogging Date: April 12, 2010 Time: 5:00pm-6:00pm Here you will learn lots of tricks and tips about SEO and Technical Blogging from various Industry Technical Blogging Experts. This event will surely be one of the most important Tech conventions of 2010. TechEd is going to be a very busy time for Tech developers and enthusiasts, since every evening there will be a fun session to attend. If you are interested in any of the above topics for every session, I suggest that you visit each of them as you will learn so many things about the topic to be discussed. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology Tagged: TechEd, TechEdIn

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  • SQL SERVER – Attach mdf file without ldf file in Database

    - by pinaldave
    Background Story: One of my friends recently called up and asked me if I had spare time to look at his database and give him a performance tuning advice. Because I had some free time to help him out, I said yes. I asked him to send me the details of his database structure and sample data. He said that since his database is in a very early stage and is small as of the moment, so he told me that he would like me to have a complete database. My response to him was “Sure! In that case, take a backup of the database and send it to me. I will restore it into my computer and play with it.” He did send me his database; however, his method made me write this quick note here. Instead of taking a full backup of the database and sending it to me, he sent me only the .mdf (primary database file). In fact, I asked for a complete backup (I wanted to review file groups, files, as well as few other details).  Upon calling my friend,  I found that he was not available. Now,  he left me with only a .mdf file. As I had some extra time, I decided to checkout his database structure and get back to him regarding the full backup, whenever I can get in touch with him again. Technical Talk: If the database is shutdown gracefully and there was no abrupt shutdown (power outrages, pulling plugs to machines, machine crashes or any other reasons), it is possible (there’s no guarantee) to attach .mdf file only to the server. Please note that there can be many more reasons for a database that is not getting attached or restored. In my case, the database had a clean shutdown and there were no complex issues. I was able to recreate a transaction log file and attached the received .mdf file. There are multiple ways of doing this. I am listing all of them here. Before using any of them, please consult the Domain Expert in your company or industry. Also, never attempt this on live/production server without the presence of a Disaster Recovery expert. USE [master] GO -- Method 1: I use this method EXEC sp_attach_single_file_db @dbname='TestDb', @physname=N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TestDb.mdf' GO -- Method 2: CREATE DATABASE TestDb ON (FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TestDb.mdf') FOR ATTACH_REBUILD_LOG GO Method 2: If one or more log files are missing, they are recreated again. There is one more method which I am demonstrating here but I have not used myself before. According to Book Online, it will work only if there is one log file that is missing. If there are more than one log files involved, all of them are required to undergo the same procedure. -- Method 3: CREATE DATABASE TestDb ON ( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA\TestDb.mdf') FOR ATTACH GO Please read the Book Online in depth and consult DR experts before working on the production server. In my case, the above syntax just worked fine as the database was clean when it was detached. Feel free to write your opinions and experiences for it will help the IT community to learn more from your suggestions and skills. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Question, SQL, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – MSQL_XP – Wait Type – Day 20 of 28

    - by pinaldave
    In this blog post, I am going to discuss something from my field experience. While consultation, I have seen various wait typed, but one of my customers who has been using SQL Server for all his operations had an interesting issue with a particular wait type. Our customer had more than 100+ SQL Server instances running and the whole server had MSSQL_XP wait type as the most number of wait types. While running sp_who2 and other diagnosis queries, I could not immediately figure out what the issue was because the query with that kind of wait type was nowhere to be found. After a day of research, I was relieved that the solution was very easy to figure out. Let us continue discussing this wait type. From Book On-Line: ?MSQL_XP occurs when a task is waiting for an extended stored procedure to end. SQL Server uses this wait state to detect potential MARS application deadlocks. The wait stops when the extended stored procedure call ends. MSQL_XP Explanation: This wait type is created because of the extended stored procedure. Extended Stored Procedures are executed within SQL Server; however, SQL Server has no control over them. Unless you know what the code for the extended stored procedure is and what it is doing, it is impossible to understand why this wait type is coming up. Reducing MSQL_XP wait: As discussed, it is hard to understand the Extended Stored Procedure if the code for it is not available. In the scenario described at the beginning of this post, our client was using third-party backup tool. The third-party backup tool was using Extended Stored Procedure. After we learned that this wait type was coming from the extended stored procedure of the backup tool they were using, we contacted the tech team of its vendor. The vendor admitted that the code was not optimal at some places, and within that day they had provided the patch. Once the updated version was installed, the issue on this wait type disappeared. As viewed in the wait statistics of all the 100+ SQL Server, there was no more MSSQL_XP wait type found. In simpler terms, you must first identify which Extended Stored Procedure is creating the wait type of MSSQL_XP and see if you can get in touch with the creator of the SP so you can help them optimize the code. If you have encountered this MSSQL_XP wait type, I encourage all of you to write how you managed it. Please do not mention the name of the vendor in your comment as I will not approve it. The focus of this blog post is to understand the wait types; not talk about others. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussion of Wait Stats in this blog is generic and varies from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – Understanding XML – Contest Win Joes 2 Pros Combo (USD 198) – Day 5 of 5

    - by pinaldave
    August 2011 we ran a contest where every day we give away one book for an entire month. The contest had extreme success. Lots of people participated and lots of give away. I have received lots of questions if we are doing something similar this month. Absolutely, instead of running a contest a month long we are doing something more interesting. We are giving away USD 198 worth gift every day for this week. We are giving away Joes 2 Pros 5 Volumes (BOOK) SQL 2008 Development Certification Training Kit every day. One copy in India and One in USA. Total 2 of the giveaway (worth USD 198). All the gifts are sponsored from the Koenig Training Solution and Joes 2 Pros. The books are available here Amazon | Flipkart | Indiaplaza How to Win: Read the Question Read the Hints Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India residents only) 2 Winners will be randomly selected announced on August 20th. Question of the Day: Is following XML a well formed XML Document? <?xml version=”1.0″?> <address> <firstname>Pinal</firstname> <lastname>Dave</lastname> <title>Founder</title> <company>SQLAuthority.com</company> </address> a) Yes b) No c) I do not know Query Hints: BIG HINT POST A common observation by people seeing an XML file for the first time is that it looks like just a bunch of data inside a text file. XML files are text-based documents, which makes them easy to read.  All of the data is literally spelled out in the document and relies on a just a few characters (<, >, =) to convey relationships and structure of the data.  XML files can be used by any commonly available text editor, like Notepad. Much like a book’s Table of Contents, your first glance at well-formed XML will tell you the subject matter of the data and its general structure. Hints appearing within the data help you to quickly identify the main theme (similar to book’s subject), its headers (similar to chapter titles or sections of a book), data elements (similar to a book’s characters or chief topics), and so forth. We’ll learn to recognize and use the structural “hints,” which are XML’s markup components (e.g., XML tags, root elements). The XML Raw and Auto modes are great for displaying data as all attributes or all elements – but not both at once. If you want your XML stream to have some of its data shown in attributes and some shown as elements, then you can use the XML Path mode. If you are using an XML Path stream, then by default all values will be shown as elements. However, it is possible to pick one or more elements to be shown with an attribute(s) as well. Additional Hints: I have previously discussed various concepts from SQL Server Joes 2 Pros Volume 5. SQL Joes 2 Pros Development Series – OpenXML Options SQL Joes 2 Pros Development Series – Preparing XML in Memory SQL Joes 2 Pros Development Series – Shredding XML SQL Joes 2 Pros Development Series – Using Root With Auto XML Mode SQL Joes 2 Pros Development Series – Using Root With Auto XML Mode SQL Joes 2 Pros Development Series – What is XML? SQL Joes 2 Pros Development Series – What is XML? – 2 Next Step: Answer the Quiz in Contact Form in following format Question - Answer Name of the country (The contest is open for USA and India) Bonus Winner Leave a comment with your favorite article from the “additional hints” section and you may be eligible for surprise gift. There is no country restriction for this Bonus Contest. Do mention why you liked it any particular blog post and I will announce the winner of the same along with the main contest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Fix: Error : 402 The data types ntext and varchar are incompatible in the equal to operator

    - by pinaldave
    Some errors are very simple to understand but the solution of the same is not easy to figure out. Here is one of the similar errors where it clearly suggests where the problem is but does not tell what is the solution. Additionally, there are multiple solutions so developers often get confused with which one is correct and which one is not correct. Let us first recreate scenario and understand where the problem is. Let us run following USE Tempdb GO CREATE TABLE TestTable (ID INT, MyText NTEXT) GO SELECT ID, MyText FROM TestTable WHERE MyText = 'AnyText' GO DROP TABLE TestTable GO When you run above script it will give you following error. Msg 402, Level 16, State 1, Line 1 The data types ntext and varchar are incompatible in the equal to operator. One of the questions I often receive is that voucher is for sure compatible to equal to operator, then why does this error show up. Well, the answer is much simpler I think we have not understood the error message properly. Please see the image below. The next and varchar are not compatible when compared with each other using equal sign. Now let us change the data type on the right side of the string to nvarchar from varchar. To do that we will put N’ before the string. USE Tempdb GO CREATE TABLE TestTable (ID INT, MyText NTEXT) GO SELECT ID, MyText FROM TestTable WHERE MyText = N'AnyText' GO DROP TABLE TestTable GO When you run above script it will give following error. Msg 402, Level 16, State 1, Line 1 The data types ntext and nvarchar are incompatible in the equal to operator. You can see that error message also suggests that now we are comparing next to nvarchar. Now as we have understood the error properly, let us see various solutions to the above problem. Solution 1: Convert the data types to match with each other using CONVERT function. Change the datatype of the MyText to nvarchar. SELECT ID, MyText FROM TestTable WHERE CONVERT(NVARCHAR(MAX), MyText) = N'AnyText' GO Solution 2: Convert the data type of columns from NTEXT to NVARCHAR(MAX) (TEXT to VARCHAR(MAX) ALTER TABLE TestTable ALTER COLUMN MyText NVARCHAR(MAX) GO Now you can run the original query again and it will work fine. Solution 3: Using LIKE command instead of Equal to command. SELECT ID, MyText FROM TestTable WHERE MyText LIKE 'AnyText' GO Well, any of the three of the solutions will work. Here is my suggestion if you can change the column data type from ntext or text to nvarchar or varchar, you should follow that path as text and ntext datatypes are marked as deprecated. All developers any way to change the deprecated data types in future, it will be a good idea to change them right early. If due to any reason you can not convert the original column use Solution 1 for temporary fix. Solution 3 is the not the best solution and use it as a last option. Did I miss any other method? If yes, please let me know and I will add the solution to original blog post with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – A Puzzle – Swap Value of Column Without Case Statement

    - by pinaldave
    For the last few weeks, I have been doing Friday Puzzles and I am really loving it. Yesterday I received a very interesting question by Navneet Chaurasia on Facebook Page. He was asked this question in one of the interview questions for job. Please read the original thread for a complete idea of the conversation. I am presenting the same question here. Puzzle Let us assume there is a single column in the table called Gender. The challenge is to write a single update statement which will flip or swap the value in the column. For example if the value in the gender column is ‘male’ swap it with ‘female’ and if the value is ‘female’ swap it with ‘male’. Here is the quick setup script for the puzzle. USE tempdb GO CREATE TABLE SimpleTable (ID INT, Gender VARCHAR(10)) GO INSERT INTO SimpleTable (ID, Gender) SELECT 1, 'female' UNION ALL SELECT 2, 'male' UNION ALL SELECT 3, 'male' GO SELECT * FROM SimpleTable GO The above query will return following result set. The puzzle was to write a single update column which will generate following result set. There are multiple answers to this simple puzzle. Let me show you three different ways. I am assuming that the column will have either value ‘male’ or ‘female’ only. Method 1: Using CASE Statement I believe this is going to be the most popular solution as we are all familiar with CASE Statement. UPDATE SimpleTable SET Gender = CASE Gender WHEN 'male' THEN 'female' ELSE 'male' END GO SELECT * FROM SimpleTable GO Method 2: Using REPLACE  Function I totally understand it is the not cleanest solution but it will for sure work in giving situation. UPDATE SimpleTable SET Gender = REPLACE(('fe'+Gender),'fefe','') GO SELECT * FROM SimpleTable GO Method 3: Using IIF in SQL Server 2012 If you are using SQL Server 2012 you can use IIF and get the same effect as CASE statement. UPDATE SimpleTable SET Gender = IIF(Gender = 'male', 'female', 'male') GO SELECT * FROM SimpleTable GO You can read my article series on SQL Server 2012 various functions over here. SQL SERVER – Denali – Logical Function – IIF() – A Quick Introduction SQL SERVER – Detecting Leap Year in T-SQL using SQL Server 2012 – IIF, EOMONTH and CONCAT Function Let us clean up. DROP TABLE SimpleTable GO Question to you: I came up with three simple tricks where there is a single UPDATE statement which swaps the values in the column. Do you know any other simple trick? If yes, please post here in the comments. I will pick two random winners from all the valid answers. Winners will get 1) Print Copy of SQL Server Interview Questions and Answers 2) Free Learning Code for Online Video Courses I will announce the winners on coming Monday. Reference:  Pinal Dave (http://blog.SQLAuthority.com) Filed under: CodeProject, PostADay, SQL, SQL Authority, SQL Interview Questions and Answers, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • SQLAuthority News – Book Signing Event – SQLPASS 2011 Event Log

    - by pinaldave
    I have been dreaming of writing book for really long time, and I finally got the chance – in fact, two chances!  I recently wrote two books: SQL Programming Joes 2 Pros: Programming and Development for Microsoft SQL Server 2008 [Amazon] | [Flipkart] | [Kindle] and SQL Wait Stats Joes 2 Pros: SQL Performance Tuning Techniques Using Wait Statistics, Types & Queues [Amazon] | [Flipkart] | [Kindle].  I had a lot of fun writing these two books, even though sometimes I had to sacrifice some family time and time for other personal development to write the books. The good side of writing book is that when the efforts put in writing books are recognize by books readers and kind organizations like expressor studio. Book Signing Event Book writing is a complex process.  Even after you spend months, maybe years, writing the material you still have to go through the editing and fact checking processes.  And, once the book is out there, there is no way to take back all the copies to change mistakes or add something you forgot.  Most of the time it is a one-way street. Book Signing Event Just like every author, I had a dream that after the books were written, they would be loved by people and gain acceptance by an audience. My first book, SQL Programming Joes 2 Pros: Programming and Development for Microsoft SQL Server 2008, is extremely popular because it helps lots of people learn various fundamental topics. My second book covers beginning to learn SQL Server Wait Stats, which is a relatively new subject. This book has had very good acceptance in the community. Book Signing Event Helping my community is my primary focus, so I was happy to see this year’s SQLPASS tag line: ‘This is a Community.‘ At the event, the expressor studio guys came up with a very novel idea. They had previously used my books and they had found them very useful. They got 100 copies of the book and decided to give it away to community folks. They invited me and my co-author Rick Morelan to hold a book signing event. We did a book signing on Thursday between 1 pm and 2 pm. Book Signing Event This event was one of the best events for me. This was my first book signing event outside of India. I reached the book signing location around 20 minutes before the scheduled time and what I saw was a big line for the book signing event. I felt very honored looking at the crowd and all the people around the event location. I felt very humbled when I saw some of my very close friends standing in the line to get my signature. It was really heartwarming to see so many enthusiasts waiting for more than an hour to get my signature. While standing in line I had the chance to have a conversation with every single person who showed up for the signature. I made sure that I repeated every single name and wrote it in every book with my signature. There is saying that if we write a name once we will remember it forever. I want to remember all of you who saw me at the book signing. Your comments were wonderful, your feedback was amazing and you were all very supportive. Book Signing Event I have made a note of every conversation I had with all of you when I was signing the books. Once again, I just want to express my thanks for coming to my book signing event. The whole experience was very humbling. On the top of it, I want to thank the expressor studio people who made it possible, who organized the whole signing event. I am so thankful to them for facilitating the whole experience, which is going to be hard to beat by any future experience. My books Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL PASS, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • SQL SERVER – Identity Fields – Contest Win Joes 2 Pros Combo (USD 198) – Day 2 of 5

    - by pinaldave
    August 2011 we ran a contest where every day we give away one book for an entire month. The contest had extreme success. Lots of people participated and lots of give away. I have received lots of questions if we are doing something similar this month. Absolutely, instead of running a contest a month long we are doing something more interesting. We are giving away USD 198 worth gift every day for this week. We are giving away Joes 2 Pros 5 Volumes (BOOK) SQL 2008 Development Certification Training Kit every day. One copy in India and One in USA. Total 2 of the giveaway (worth USD 198). All the gifts are sponsored from the Koenig Training Solution and Joes 2 Pros. The books are available here Amazon | Flipkart | Indiaplaza How to Win: Read the Question Read the Hints Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India residents only) 2 Winners will be randomly selected announced on August 20th. Question of the Day: Which of the following statement is incorrect? a) Identity value can be negative. b) Identity value can have negative interval. c) Identity value can be of datatype VARCHAR d) Identity value can have increment interval larger than 1 Query Hints: BIG HINT POST A simple way to determine if a table contains an identity field is to use the SSMS Object Explorer Design Interface. Navigate to the table, then right-click it and choose Design from the pop-up window. When your design tab opens, select the first field in the table to view its list of properties in the lower pane of the tab (In this case the field is ProductID). Look to see if the Identity Specification property in the lower pane is set to either yes or no. SQL Server will allow you to utilize IDENTITY_INSERT with just one table at a time. After you’ve completed the needed work, it’s very important to reset the IDENTITY_INSERT back to OFF. Additional Hints: I have previously discussed various concepts from SQL Server Joes 2 Pros Volume 2. SQL Joes 2 Pros Development Series – Output Clause in Simple Examples SQL Joes 2 Pros Development Series – Ranking Functions – Advanced NTILE in Detail SQL Joes 2 Pros Development Series – Ranking Functions – RANK( ), DENSE_RANK( ), and ROW_NUMBER( ) SQL Joes 2 Pros Development Series – Advanced Aggregates with the Over Clause SQL Joes 2 Pros Development Series – Aggregates with the Over Clause SQL Joes 2 Pros Development Series – Overriding Identity Fields – Tricks and Tips of Identity Fields SQL Joes 2 Pros Development Series – Many to Many Relationships Next Step: Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India) Bonus Winner Leave a comment with your favorite article from the “additional hints” section and you may be eligible for surprise gift. There is no country restriction for this Bonus Contest. Do mention why you liked it any particular blog post and I will announce the winner of the same along with the main contest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Monthly list of Puzzles and Solutions on SQLAuthority.com

    - by pinaldave
    This month has been very interesting month for SQLAuthority.com we had multiple and various puzzles which everybody participated and lots of interesting conversation which we have shared. Let us start in latest puzzles and continue going down. There are few answers also posted on facebook as well. SQL SERVER – Puzzle Involving NULL – Resolve – Error – Operand data type void type is invalid for sum operator This puzzle involves NULL and throws an error. The challenge is to resolve the error. There are multiple ways to resolve this error. Readers has contributed various methods. Few of them even have supplied the answer why this error is showing up. NULL are very important part of the database and if one of the column has NULL the result can be totally different than the one expected. SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers I modified script provided by friend to find greatest number between two number. My script has small bug in it. However, lots of readers have suggested better scripts. Madhivanan has written blog post on the subject over here. SQL SERVER – BI Quiz Hint – Performance Tuning Cubes – Hints This quiz is hosted on my friend Jacob‘s site. I have written many hints how one can tune cubes. Now one can take part here and win exciting prizes. SQL SERVER – Solution – Generating Zero Without using Any Numbers in T-SQL Madhivanan has asked very interesting question on his blog about How to Generate Zero without using Any Numbers in T-SQL. He has demonstrated various methods how one can generate Zero. I asked the same question on blog and got many interesting answers which I have shared. SQL SERVER – Solution – Puzzle – Statistics are not Updated but are Created Once I have to accept that this was most difficult puzzle. In this puzzle I have asked even though settings are correct, why statistics of the tables are not getting updated. In this puzzle one is tested with various concepts 1) Indexes, 2) Statistics, 3) database settings etc. There are multiple ways of solving this puzzles. It was interesting as many took interest but only few got it right. SQL SERVER – Question to You – When to use Function and When to use Stored Procedure This is rather straight forward question and not the typical puzzle. The answers from readers are great however, still there is chance of more detailed answers. SQL SERVER – Selecting Domain from Email Address I wrote on selecting domains from email addresses. Madhivanan makes puzzle out of a simple question. He wrote a follow-up post over here. In his post he writes various way how one can find email addresses from list of domains. Well, this is not a puzzle but amazing Guest Post by Feodor Georgiev who has written on subject Job Interviewing the Right Way (and for the Right Reasons). An article which everyone should read. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • Big Data – Operational Databases Supporting Big Data – Key-Value Pair Databases and Document Databases – Day 13 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the Relational Database and NoSQL database in the Big Data Story. In this article we will understand the role of Key-Value Pair Databases and Document Databases Supporting Big Data Story. Now we will see a few of the examples of the operational databases. Relational Databases (Yesterday’s post) NoSQL Databases (Yesterday’s post) Key-Value Pair Databases (This post) Document Databases (This post) Columnar Databases (Tomorrow’s post) Graph Databases (Tomorrow’s post) Spatial Databases (Tomorrow’s post) Key Value Pair Databases Key Value Pair Databases are also known as KVP databases. A key is a field name and attribute, an identifier. The content of that field is its value, the data that is being identified and stored. They have a very simple implementation of NoSQL database concepts. They do not have schema hence they are very flexible as well as scalable. The disadvantages of Key Value Pair (KVP) database are that they do not follow ACID (Atomicity, Consistency, Isolation, Durability) properties. Additionally, it will require data architects to plan for data placement, replication as well as high availability. In KVP databases the data is stored as strings. Here is a simple example of how Key Value Database will look like: Key Value Name Pinal Dave Color Blue Twitter @pinaldave Name Nupur Dave Movie The Hero As the number of users grow in Key Value Pair databases it starts getting difficult to manage the entire database. As there is no specific schema or rules associated with the database, there are chances that database grows exponentially as well. It is very crucial to select the right Key Value Pair Database which offers an additional set of tools to manage the data and provides finer control over various business aspects of the same. Riak Rick is one of the most popular Key Value Database. It is known for its scalability and performance in high volume and velocity database. Additionally, it implements a mechanism for collection key and values which further helps to build manageable system. We will further discuss Riak in future blog posts. Key Value Databases are a good choice for social media, communities, caching layers for connecting other databases. In simpler words, whenever we required flexibility of the data storage keeping scalability in mind – KVP databases are good options to consider. Document Database There are two different kinds of document databases. 1) Full document Content (web pages, word docs etc) and 2) Storing Document Components for storage. The second types of the document database we are talking about over here. They use Javascript Object Notation (JSON) and Binary JSON for the structure of the documents. JSON is very easy to understand language and it is very easy to write for applications. There are two major structures of JSON used for Document Database – 1) Name Value Pairs and 2) Ordered List. MongoDB and CouchDB are two of the most popular Open Source NonRelational Document Database. MongoDB MongoDB databases are called collections. Each collection is build of documents and each document is composed of fields. MongoDB collections can be indexed for optimal performance. MongoDB ecosystem is highly available, supports query services as well as MapReduce. It is often used in high volume content management system. CouchDB CouchDB databases are composed of documents which consists fields and attachments (known as description). It supports ACID properties. The main attraction points of CouchDB are that it will continue to operate even though network connectivity is sketchy. Due to this nature CouchDB prefers local data storage. Document Database is a good choice of the database when users have to generate dynamic reports from elements which are changing very frequently. A good example of document usages is in real time analytics in social networking or content management system. Tomorrow In tomorrow’s blog post we will discuss about various other Operational Databases supporting Big Data. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – Introduction to Big Data – Guest Post

    - by pinaldave
    BIG Data – such a big word – everybody talks about this now a days. It is the word in the database world. In one of the conversation I asked my friend Jasjeet Sigh the same question – what is Big Data? He instantly came up with a very effective write-up.  Jasjeet is working as a Technical Manager with Koenig Solutions. He leads the SQL domain, and holds rich IT industry experience. Talking about Koenig, it is a 19 year old IT training company that offers several certification choices. Some of its courses include SharePoint Training, Project Management certifications, Microsoft Trainings, Business Intelligence programs, Web Design and Development courses etc. Big Data, as the name suggests, is about data that is BIG in nature. The data is BIG in terms of size, and it is difficult to manage such enormous data with relational database management systems that are quite popular these days. Big Data is not just about being large in size, it is also about the variety of the data that differs in form or type. Some examples of Big Data are given below : Scientific data related to weather and atmosphere, Genetics etc Data collected by various medical procedures, such as Radiology, CT scan, MRI etc Data related to Global Positioning System Pictures and Videos Radio Frequency Data Data that may vary very rapidly like stock exchange information Apart from difficulties in managing and storing such data, it is difficult to query, analyze and visualize it. The characteristics of Big Data can be defined by four Vs: Volume: It simply means a large volume of data that may span Petabyte, Exabyte and so on. However it also depends organization to organization that what volume of data they consider as Big Data. Variety: As discussed above, Big Data is not limited to relational information or structured Data. It can also include unstructured data like pictures, videos, text, audio etc. Velocity:  Velocity means the speed by which data changes. The higher is the velocity, the more efficient should be the system to capture and analyze the data. Missing any important point may lead to wrong analysis or may even result in loss. Veracity: It has been recently added as the fourth V, and generally means truthfulness or adherence to the truth. In terms of Big Data, it is more of a challenge than a characteristic. It is difficult to ascertain the truth out of the enormous amount of data and the one that has high velocity. There are always chances of having un-precise and uncertain data. It is a challenging task to clean such data before it is analyzed. Big Data can be considered as the next big thing in the IT sector in terms of innovation and development. If appropriate technologies are developed to analyze and use the information, it can be the driving force for almost all industrial segments. These include Retail, Manufacturing, Service, Finance, Healthcare etc. This will help them to automate business decisions, increase productivity, and innovate and develop new products. Thanks Jasjeet Singh for an excellent write up.  Jasjeet Sign is working as a Technical Manager with Koenig Solutions. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Database, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Big Data

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  • SQL SERVER – Clustered Index and Primary Key – Contest Win Joes 2 Pros Combo (USD 198) – Day 3 of 5

    - by pinaldave
    August 2011 we ran a contest where every day we give away one book for an entire month. The contest had extreme success. Lots of people participated and lots of give away. I have received lots of questions if we are doing something similar this month. Absolutely, instead of running a contest a month long we are doing something more interesting. We are giving away USD 198 worth gift every day for this week. We are giving away Joes 2 Pros 5 Volumes (BOOK) SQL 2008 Development Certification Training Kit every day. One copy in India and One in USA. Total 2 of the giveaway (worth USD 198). All the gifts are sponsored from the Koenig Training Solution and Joes 2 Pros. The books are available here Amazon | Flipkart | Indiaplaza How to Win: Read the Question Read the Hints Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India residents only) 2 Winners will be randomly selected announced on August 20th. Question of the Day: Which of the following datatype is usually NOT the best choice for Primary Key and Clustered Index? a) INT b) BIGINT c) GUID d) SMALLINT Query Hints: BIG HINT POST The clustered index is the placement order of a table’s records in memory pages. When you insert new records, then each record will be inserted into the memory page in the order it belongs. In the figure below we see another new record (Major Disarray) being inserted, in sequence, between Jonny and Rick. Since there is no room in this memory page, some records will need to shift around. The page split occurs when Irenes’ record moves to the second page. Page splits are considered very bad for performance, and there are a number of techniques to reduce, or even eliminate, the risk of page splits. You can create a clustered index on the table on any field you choose. Sometime SQL will create a clustered index for you. Often times the field having the Primary Key makes a great candidate for the clustered index. Additional Hints: I have previously discussed various concepts from SQL Server Joes 2 Pros Volume 3. SQL Joes 2 Pros Development Series – All about SQL Statistics SQL Joes 2 Pros Development Series – Introduction to Page Split SQL Joes 2 Pros Development Series – The Clustered Index – Simple Understanding SQL Joes 2 Pros Development Series – Geography Data Type – Calculating Distance Between Two Points on the Earth SQL Joes 2 Pros Development Series – Sparse Data and Space Used by Sparse Data SQL Joes 2 Pros Development Series – System and Time Data Types SQL Joes 2 Pros Development Series – Data Row Space Usage and NULL Storage Next Step: Answer the Quiz in Contact Form in following format Question Answer Name of the country (The contest is open for USA and India) Bonus Winner Leave a comment with your favorite article from the “additional hints” section and you may be eligible for surprise gift. There is no country restriction for this Bonus Contest. Do mention why you liked it any particular blog post and I will announce the winner of the same along with the main contest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQLAuthority News – Random Thoughts and Random Ideas

    - by pinaldave
    There are days when I keep on wondering about SQL, and even my life overall. Today is Saturday so I decided to write about SQL Server. Just like any other mornings, I woke up at 5 and opened my blog editor. I usually do not open Twitter or Facebook when I am planning to focus on my work, as they are little distractions for me. But today I opened my Twitter account and came across a very interesting quote from a friend: ‘Can I expect you to be different today?’ Well, I think it was very powerful quote for me to read first thing on a new day. This quote froze me for a while and made me think, “Do I really want to write about an SQL Server tip, or something different?”  After a little thinking, I’ve realized that for today I would go on and write something different. I am going to write about a few of the ideas and thoughts I had yesterday. After writing all these, I realized that if I am thinking so much in a day, and if I write a blog post of my random musing of the week or month, it can be so long (and boring). Here are some of my random thoughts I’d like to share with you: When the airplane lands, why does everybody get up and try to rush out when their luggage would be coming probably 20-30 minutes later? I really do not like this question when it was asked to me: “SQL Server is not using optimal index which I just created – how can I force it?” I am not going elaborate on this statement but you are allowed to in the comment section. Why do some people wish Good Morning even when they meet us after 4 PM? Can I optimize a query so much that it gives me a result before I execute it? Is it corruption when someone does their personal household work at office? The lane where I drive is always the slowest lane. Why waste time on correcting others when there are a lot of pending improvements for ourselves? If I have to get Tattoo, which SQL Server Execution Plan symbol should I get? Why do I reach office so early that the coffee machine is yet running its daily cleaning job? Why does every laptop have a ‘Page Up’ key at different locations on the keyboard? While I like color movies, I really appreciate black and white photographs. I do not appreciate statements like, “If I receive your books in PDF, I will spread it to many people to give you much greater exposure. So would you please send them to me ASAP?” Do not tell me, “Why does the database grow back after shrinking it every day?” I suggest you use “Search this blog” for the explanation. Petrol prices are currently at INR 74. I hope the rate remains there. Let me ask you the same question which started my day today:  “Can I expect you to be different today?” Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Identifying Column Data Type of uniqueidentifier without Querying System Tables

    - by pinaldave
    I love interesting conversations with related to SQL Server. One of my friends Madhivanan always comes up with an interesting point of conversation. Here is one of the conversation between us. I am very confident this blog post will for sure enable you with some new knowledge. Madhi: How do I know if any table has a uniqueidentifier column used in it? Pinal:  I am sure you know that you can do it through some DMV or catalogue views. Madhi: I know that but how can we do that without using DMV or catalogue views? Pinal: Hm… what can I use? Madhi: You can use table name. Pinal: Easy, just say SELECT YourUniqueIdentCol FROM Table. Madhi: Hold on, the question seems to be not clear to you – you do know the name of the column. The matter of the fact, you do not know if the table has uniqueidentifier column. Only information you have is table name. Pinal: Madhi, this seems like you are changing the question when I am close to answer. Madhi: Well, are you clear now? Let me say it again – How do I know if any table has a uniqueidentifier column and what is its value without using any DMV or System Catalogues? Only information you know is table name and you are allowed to return any kind of error if table does not have uniqueidentifier column. Pinal: Do you know the answer? Madhi: Yes. I just wanted to test your knowledge about SQL. Pinal: I will have to think. Let me accept I do not know it right away. Can you share the answer please? Madhi: I won! Here it goes! Pinal: When I have friends like you – who needs enemies? Madhi: (laughter which did not stop for a minute). CREATE TABLE t ( GuidCol UNIQUEIDENTIFIER DEFAULT newsequentialid() ROWGUIDCOL, data VARCHAR(60) ) INSERT INTO t (data) SELECT 'test' INSERT INTO t (data) SELECT 'test1' SELECT $rowguid FROM t DROP TABLE t This is indeed very interesting to me. Please note that this is not the optimal way and there will be many other ways to retrieve uniqueidentifier name and value. What I learned from this was if I am in a rush to check if the table has uniqueidentifier and I do not know the name of the same, I can use SELECT TOP (1) $rowguid and quickly know the name of the column. I can later use the same columnname in my query. Madhi did teach me this new trick. Did you know this? What are other ways to get the check uniqueidentifier column existence in a database? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Finding Different ColumnName From Almost Identitical Tables

    - by pinaldave
    I have mentioned earlier on this blog that I love social media – Facebook and Twitter. I receive so many interesting questions that sometimes I wonder how come I never faced them in my real life scenario. Well, let us see one of the similar situation. Here is one of the questions which I received on my social media handle. “Pinal, I have a large database. I did not develop this database but I have inherited this database. In our database we have many tables but all the tables are in pairs. We have one archive table and one current table. Now here is interesting situation. For a while due to some reason our organization has stopped paying attention to archive data. We did not archive anything for a while. If this was not enough we  even changed the schema of current table but did not change the corresponding archive table. This is now becoming a huge huge problem. We know for sure that in current table we have added few column but we do not know which ones. Is there any way we can figure out what are the new column added in the current table and does not exist in the archive tables? We cannot use any third party tool. Would you please guide us?” Well here is the interesting example of how we can use sys.column catalogue views and get the details of the newly added column. I have previously written about EXCEPT over here which is very similar to MINUS of Oracle. In following example we are going to create two tables. One of the tables has extra column. In our resultset we will get the name of the extra column as we are comparing the catalogue view of the column name. USE AdventureWorks2012 GO CREATE TABLE ArchiveTable (ID INT, Col1 VARCHAR(10), Col2 VARCHAR(100), Col3 VARCHAR(100)); CREATE TABLE CurrentTable (ID INT, Col1 VARCHAR(10), Col2 VARCHAR(100), Col3 VARCHAR(100), ExtraCol INT); GO -- Columns in ArchiveTable but not in CurrentTable SELECT name ColumnName FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'ArchiveTable' EXCEPT SELECT name ColumnName FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'CurrentTable' GO -- Columns in CurrentTable but not in ArchiveTable SELECT name ColumnName FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'CurrentTable' EXCEPT SELECT name ColumnName FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'ArchiveTable' GO DROP TABLE ArchiveTable; DROP TABLE CurrentTable; GO The above query will return us following result. I hope this solves the problems. It is not the most elegant solution ever possible but it works. Here is the puzzle back to you – what native T-SQL solution would you have provided in this situation? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Last Two Days to Get FREE Book – Joes 2 Pros Certification 70-433

    - by pinaldave
    Earlier this week we announced that we will be giving away FREE SQL Wait Stats book to everybody who will get SQL Server Joes 2 Pros Combo Kit. We had a fantastic response to the contest. We got an overwhelming response to the offer. We knew there would be a great response but we want to honestly say thank you to all of you for making it happen. Rick and I want to make sure that we express our special thanks to all of you who are reading our books. The offer is still on and there are two more days to avail this offer. We want to make sure that everybody who buys our most selling combo kits, we will send our other most popular SQL Wait Stats book. Please read all the details of the offer here. The books are great resources for anyone who wants to learn SQL Server from fundamentals and eventually go on the certification path of 70-433. Exam 70-433 contains following important subject and the book covers the subject of fundamental. If you are taking the exam or not taking the exam – this book is for every SQL Developer to learn the subject from fundamentals.  Create and alter tables. Create and alter views. Create and alter indexes. Create and modify constraints. Implement data types. Implement partitioning solutions. Create and alter stored procedures. Create and alter user-defined functions (UDFs). Create and alter DML triggers. Create and alter DDL triggers. Create and deploy CLR-based objects. Implement error handling. Manage transactions. Query data by using SELECT statements. Modify data by using INSERT, UPDATE, and DELETE statements. Return data by using the OUTPUT clause. Modify data by using MERGE statements. Implement aggregate queries. Combine datasets. INTERSECT, EXCEPT Implement subqueries. Implement CTE (common table expression) queries. Apply ranking functions. Control execution plans. Manage international considerations. Integrate Database Mail. Implement full-text search. Implement scripts by using Windows PowerShell and SQL Server Management Objects (SMOs). Implement Service Broker solutions. Track data changes. Data capture Retrieve relational data as XML. Transform XML data into relational data. Manage XML data. Capture execution plans. Collect output from the Database Engine Tuning Advisor. Collect information from system metadata. Availability of Book USA - Amazon | India - Flipkart | Indiaplaza Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Joes 2 Pros, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL Authority News – Presenting at SQL Bangalore on May 3, 2014 – Performing an Effective Presentation

    - by Pinal Dave
    SQL Bangalore is a wonderful community and we always have a great response when we present on technology. It is SQL User Group and we discuss everything SQL there. This month we have SQL Server 2014 theme and we are going to have a community launch on this subject. We have the best of the best speakers presenting on SQL Server 2014 technology. Looking at the whole line of celebrity speakers, I have decided not to present on SQL Server. I will be presenting on the performance tuning subject, but with the twist of soft skills. I will be presenting on “Performing an Effective Presentation“. Trust me, you do not want to miss this presentation, I will be presenting on how to present effectively when presenting SQL Server topics. What this session will NOT have I personally believe that we all are good presenters most of the time. We can all easily call out if someone is bad presenter. There is no point talking about basics like bigger bullet points, talk loudly, talk with confidence, use better analogies etc. In simple words – this is not going to some philosophy session and boring notes. What this session will have Well, this session will tell stories of my life. It will tell how we can present about technology and SQL Server with the help of stories and personal experience. I am going to tell stories about two legends  who have inspired me. Right after that we will be doing two exercises together where we will learn quickly and effectively, how to become better speaker – instantly! There is no video recording of this session. If you want to get resources from this session, please sign up my newsletter at http://bit.ly/sqllearn Here are few of the slides from this presentation: Here is the details about the event and location Venue:Microsoft Corporation, Signature Building,Embassy Golf Links Business Park, Intermediate Ring Road, Domlur, Bangalore – 560071 The agenda is amazing – we have top line SQL Speakers. Everyone is welcome and don’t forget to get your friend along for this event. Loads to learn and tons to share !!! Keynote (20 mins) by Anupam Tiwari – Business Program Manager – GTSC Backup Enhancements with SQL Server 2014 by Amit Banerjee – PFE Microsoft Performance Enhancements with SQL Server 2014 by Sourabh Agarwal - PFE Microsoft LUNCH BREAK Performing an effective Presentation by Pinal Dave – Community Member (SQLAuthority.com) InMemory Enhancements with SQL Server 2014 by Balmukund Lakhani – Support Escalation Engg. Microsoft Some more lesser known enhancements with SQL Server 2014 by Vinod Kumar – Technical Architect Microsoft MTC Power Packed – Power BI with SQL Server by Kane Conway – Support Escalation Engg. Microsoft I am very big fan of Amit, Balmukund and Vinod – I have always watched their session and this time, I am going to once again attend their session without missing a single min. They are SQL legends, I am going to be there and learn when they are sharing their knowledge.  Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL

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  • SQL SERVER – How to Get SQL Server Restart Notification?

    - by Pinal Dave
    Few days back my friend called me to know if there is any tool which can be used to get restart notification about SQL in their environment. I told that SQL Server can do it by itself with some configurations. He was happy and surprised to know that he need not spend any extra money. In SQL Server, we can configure stored procedure(s) to run at start-up of SQL Server. This blog would give steps to achieve how to achieve it. There are many situations where this feature can be used. Below are few. Logging SQL Server startup timings Modify data in some table during startup (i.e. table in tempdb) Sending notification about SQL start. Step 1 – Enable ‘scan for startup procs’ This can be done either using T-SQL or User Interface of Management Studio. EXEC sys.sp_configure N'Show Advanced Options', N'1' GO RECONFIGURE WITH OVERRIDE GO EXEC sys.sp_configure N'scan for startup procs', N'1' GO RECONFIGURE WITH OVERRIDE GO Below is the interface to change the setting. We need to go to “Server” > “Properties” and use “Advanced” tab. “Scan for Startup Procs” is the parameter under “Miscellaneous” section as shown below. We need to make value as “True” and hit OK. Step 2 – Create stored procedure It’s important to note that the procedure is executed after recovery is finished for ALL databases. Here is a sample stored procedure. You can use your own logic in the procedure. CREATE PROCEDURE SQLStartupProc AS BEGIN CREATE TABLE ##ThisTableShouldAlwaysExists (AnyColumn INT) END Step 3 – Set Procedure to run at startup We need to use sp_procoption to mark the procedure to run at startup. Here is the code to let SQL know that this is startup proc. sp_procoption 'SQLStartupProc', 'startup', 'true' This can be used only for procedures in master database. Msg 15398, Level 11, State 1, Procedure sp_procoption, Line 89 Only objects in the master database owned by dbo can have the startup setting changed. We also need to remember that such procedure should not have any input/output parameter. Here is the error which would be raised. Msg 15399, Level 11, State 1, Procedure sp_procoption, Line 107 Could not change startup option because this option is restricted to objects that have no parameters. Verification Here is the query to find which procedures is marked as startup procedures. SELECT name FROM sys.objects WHERE OBJECTPROPERTY(OBJECT_ID, 'ExecIsStartup') = 1 Once this is done, I have restarted SQL instance and here is what we would see in SQL ERRORLOG Launched startup procedure 'SQLStartupProc'. This confirms that stored procedure is executed. You can also notice that this is done after all databases are recovered. Recovery is complete. This is an informational message only. No user action is required. After few days my friend again called me and asked – I want to turn this OFF? Use comments section and post the answer for him.  Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL

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  • Mysql optimization question - How to apply AND logic in search and limit on results in one query?

    - by sandeepan-nath
    This is a little long but I have provided all the database structures and queries so that you can run it immediately and help me. Run the following queries:- CREATE TABLE IF NOT EXISTS `Tutor_Details` ( `id_tutor` int(10) NOT NULL auto_increment, `firstname` varchar(100) NOT NULL default '', `surname` varchar(155) NOT NULL default '', PRIMARY KEY (`id_tutor`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=41 ; INSERT INTO `Tutor_Details` (`id_tutor`,`firstname`, `surname`) VALUES (1, 'Sandeepan', 'Nath'), (2, 'Bob', 'Cratchit'); CREATE TABLE IF NOT EXISTS `Classes` ( `id_class` int(10) unsigned NOT NULL auto_increment, `id_tutor` int(10) unsigned NOT NULL default '0', `class_name` varchar(255) default NULL, PRIMARY KEY (`id_class`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=229 ; INSERT INTO `Classes` (`id_class`,`class_name`, `id_tutor`) VALUES (1, 'My Class', 1), (2, 'Sandeepan Class', 2); CREATE TABLE IF NOT EXISTS `Tags` ( `id_tag` int(10) unsigned NOT NULL auto_increment, `tag` varchar(255) default NULL, PRIMARY KEY (`id_tag`), UNIQUE KEY `tag` (`tag`), KEY `id_tag` (`id_tag`), KEY `tag_2` (`tag`), KEY `tag_3` (`tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=18 ; INSERT INTO `Tags` (`id_tag`, `tag`) VALUES (1, 'Bob'), (6, 'Class'), (2, 'Cratchit'), (4, 'Nath'), (3, 'Sandeepan'), (5, 'My'); CREATE TABLE IF NOT EXISTS `Tutors_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_tutor` int(10) default NULL, KEY `Tutors_Tag_Relations` (`id_tag`), KEY `id_tutor` (`id_tutor`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Tutors_Tag_Relations` (`id_tag`, `id_tutor`) VALUES (3, 1), (4, 1), (1, 2), (2, 2); CREATE TABLE IF NOT EXISTS `Class_Tag_Relations` ( `id_tag` int(10) unsigned NOT NULL default '0', `id_class` int(10) default NULL, `id_tutor` int(10) NOT NULL, KEY `Class_Tag_Relations` (`id_tag`), KEY `id_class` (`id_class`), KEY `id_tag` (`id_tag`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; INSERT INTO `Class_Tag_Relations` (`id_tag`, `id_class`, `id_tutor`) VALUES (5, 1, 1), (6, 1, 1), (3, 2, 2), (6, 2, 2); Following is about the tables:- There are tutors who create classes. Tutor_Details - Stores tutors Classes - Stores classes created by tutors And for searching we are using a tags based approach. All the keywords are stored in tags table (while classes/tutors are created) and tag relations are entered in Tutor_Tag_Relations and Class_Tag_Relations tables (for tutors and classes respectively)like this:- Tags - id_tag tag (this is a a unique field) Tutors_Tag_Relations - Stores tag relations while the tutors are created. Class_Tag_Relations - Stores tag relations while any tutor creates a class In the present data in database, tutor "Sandeepan Nath" has has created class "My Class" and "Bob Cratchit" has created "Sandeepan Class". 3.Requirement The requirement is to return tutor records from Tutor_Details table such that all the search terms (AND logic) are present in the union of these two sets - 1. Tutor_Details table 2. classes created by a tutor in Classes table) Example search and expected results:- Search Term Result "Sandeepan Class" Tutor Sandeepan Nath's record from Tutor Details table "Class" Both the tutors from ... Most importantly, there should be only one mysql query and a LIMIT applicable on the number of results. Following is a working query which I have so far written (It just applies OR logic of search key words instead of the desired AND logic). SELECT td . * FROM Tutor_Details AS td LEFT JOIN Tutors_Tag_Relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor LEFT JOIN Classes AS wc ON td.id_tutor = wc.id_tutor INNER JOIN Class_Tag_Relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN Tags AS t ON t.id_tag = ttagrels.id_tag OR t.id_tag = wtagrels.id_tag WHERE t.tag LIKE '%Sandeepan%' OR t.tag LIKE '%Nath%' GROUP BY td.id_tutor LIMIT 20 Please help me with anything you can. Thanks

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  • which one consume less resources? opening text file or make an sql query,both a thousand times ?

    - by imin
    hi I've a php website which displays recipes www.trymasak.my, to be exact. The recipes being displayed at the index page is updated about once a day. To get the latest recipes, I just use a mysql query which is something like "select recipe_name, page_views, image from table order by last_updated". So if I got 10000 visitors a day, obviously the query would be made 10000 times a day. A friend told me a better way (in terms of reducing server load) is when I update the recipes, I just put in the latest recipe details (names,images etc) into a text file, and make my page instead of querying a same query for 10,000 times, just get the data from the text file. Is his suggestion really better? If yes, which is the best php command should I use to open, read and close the text file? thanks

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  • Simple PHP Array Problem - IF EXIT

    - by elmas
    Hi, how can i convert this into an array? if someone searches for "lo" he gets the text "no query", but how can i do this for more words? i tried it with array('1','2').. if ($query == 'lo') { exit ('No Query.'); } i want something like this if ($query == 'lo', 'mip', 'get') { exit ('No Query.'); } so, if someone types mip he gets the message.. thank you!!

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