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  • SQL SERVER – 3 Online SQL Courses at Pluralsight and Free Learning Resources

    - by pinaldave
    Usain Bolt is an inspiration for all. He broke his own record multiple times because he wanted to do better! Read more about him on wikipedia. He is great and indeed fastest man on the planet. Usain Bolt – World’s Fastest Man “Can you teach me SQL Server Performance Tuning?” This is one of the most popular questions which I receive all the time. The answer is YES. I would love to do performance tuning training for anyone, anywhere.  It is my favorite thing to do, and it is my favorite thing to train others in.  If possible, I would love to do training 24 hours a day, 7 days a week, 365 days a year.  To me, it doesn’t feel like a job. Of course, as much as I would love to do performance tuning 24/7/365, obviously I am just one human being and can only be in one place t one time.  It is also very difficult to train more than one person at a time, and it is difficult to train two or more people at a time, especially when the two people are at different levels.  I am also limited by geography.  I live in India, and adjust to my own time zone.  Trying to teach a live course from India to someone whose time zone is 12 or more hours off of mine is very difficult.  If I am trying to teach at 2 am, I am sure I am not at my best! There was only one solution to scale – Online Trainings. I have built 3 different courses on SQL Server Performance Tuning with Pluralsight. Now I have no problem – I am 100% scalable and available 24/7 and 365. You can make me say the same things again and again till you find it right. I am in your mobile, PC as well as on XBOX. This is why I am such a big fan of online courses.  I have recorded many performance tuning classes and you can easily access them online, at your own time.  And don’t think that just because these aren’t live classes you won’t be able to get any feedback from me.  I encourage all my viewers to go ahead and ask me questions by e-mail, Twitter, Facebook, or whatever way you can get a hold of me. Here are details of three of my courses with Pluralsight. I suggest you go over the description of the course. As an author of the course, I have few FREE codes for watching the free courses. Please leave a comment with your valid email address, I will send a few of them to random winners. SQL Server Performance: Introduction to Query Tuning  SQL Server performance tuning is an art to master – for developers and DBAs alike. This course takes a systematic approach to planning, analyzing, debugging and troubleshooting common query-related performance problems. This includes an introduction to understanding execution plans inside SQL Server. In this almost four hour course we cover following important concepts. Introduction 10:22 Execution Plan Basics 45:59 Essential Indexing Techniques 20:19 Query Design for Performance 50:16 Performance Tuning Tools 01:15:14 Tips and Tricks 25:53 Checklist: Performance Tuning 07:13 The duration of each module is mentioned besides the name of the module. SQL Server Performance: Indexing Basics This course teaches you how to master the art of performance tuning SQL Server by better understanding indexes. In this almost two hour course we cover following important concepts. Introduction 02:03 Fundamentals of Indexing 22:21 Practical Indexing Implementation Techniques 37:25 Index Maintenance 16:33 Introduction to ColumnstoreIndex 08:06 Indexing Practical Performance Tips and Tricks 24:56 Checklist : Index and Performance 07:29 The duration of each module is mentioned besides the name of the module. SQL Server Questions and Answers This course is designed to help you better understand how to use SQL Server effectively. The course presents many of the common misconceptions about SQL Server, and then carefully debunks those misconceptions with clear explanations and short but compelling demos, showing you how SQL Server really works. In this almost 2 hours and 15 minutes course we cover following important concepts. Introduction 00:54 Retrieving IDENTITY value using @@IDENTITY 08:38 Concepts Related to Identity Values 04:15 Difference between WHERE and HAVING 05:52 Order in WHERE clause 07:29 Concepts Around Temporary Tables and Table Variables 09:03 Are stored procedures pre-compiled? 05:09 UNIQUE INDEX and NULLs problem 06:40 DELETE VS TRUNCATE 06:07 Locks and Duration of Transactions 15:11 Nested Transaction and Rollback 09:16 Understanding Date/Time Datatypes 07:40 Differences between VARCHAR and NVARCHAR datatypes 06:38 Precedence of DENY and GRANT security permissions 05:29 Identify Blocking Process 06:37 NULLS usage with Dynamic SQL 08:03 Appendix Tips and Tricks with Tools 20:44 The duration of each module is mentioned besides the name of the module. SQL in Sixty Seconds You will have to login and to get subscribed to the courses to view them. Here are my free video learning resources SQL in Sixty Seconds. These are 60 second video which I have built on various subjects related to SQL Server. Do let me know what you think about them? Here are three of my latest videos: Identify Most Resource Intensive Queries – SQL in Sixty Seconds #028 Copy Column Headers from Resultset – SQL in Sixty Seconds #027 Effect of Collation on Resultset – SQL in Sixty Seconds #026 You can watch and learn at your own pace.  Then you can easily ask me any questions you have.  E-mail is easiest, but for really tough questions I’m willing to talk on Skype, Gtalk, or even Facebook chat.  Please do watch and then talk with me, I am always available on the internet! Here is the video of the world’s fastest man.Usain St. Leo Bolt inspires us that we all do better than best. We can go the next level of our own record. We all can improve if we have a will and dedication.  Watch the video from 5:00 mark. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLServer, T SQL, Technology, Video

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  • SQL SERVER – Weekly Series – Memory Lane – #035

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Row Overflow Data Explanation  In SQL Server 2005 one table row can contain more than one varchar(8000) fields. One more thing, the exclusions has exclusions also the limit of each individual column max width of 8000 bytes does not apply to varchar(max), nvarchar(max), varbinary(max), text, image or xml data type columns. Comparison Index Fragmentation, Index De-Fragmentation, Index Rebuild – SQL SERVER 2000 and SQL SERVER 2005 An old but like a gold article. Talks about lots of concepts related to Index and the difference from earlier version to the newer version. I strongly suggest that everyone should read this article just to understand how SQL Server has moved forward with the technology. Improvements in TempDB SQL Server 2005 had come up with quite a lots of improvements and this blog post describes them and explains the same. If you ask me what is my the most favorite article from early career. I must point out to this article as when I wrote this one I personally have learned a lot of new things. Recompile All The Stored Procedure on Specific TableI prefer to recompile all the stored procedure on the table, which has faced mass insert or update. sp_recompiles marks stored procedures to recompile when they execute next time. This blog post explains the same with the help of a script.  2008 SQLAuthority Download – SQL Server Cheatsheet You can download and print this cheat sheet and use it for your personal reference. If you have any suggestions, please let me know and I will see if I can update this SQL Server cheat sheet. Difference Between DBMS and RDBMS What is the difference between DBMS and RDBMS? DBMS – Data Base Management System RDBMS – Relational Data Base Management System or Relational DBMS High Availability – Hot Add Memory Hot Add CPU and Hot Add Memory are extremely interesting features of the SQL Server, however, personally I have not witness them heavily used. These features also have few restriction as well. I blogged about them in detail. 2009 Delete Duplicate Rows I have demonstrated in this blog post how one can identify and delete duplicate rows. Interesting Observation of Logon Trigger On All Servers – Solution The question I put forth in my previous article was – In single login why the trigger fires multiple times; it should be fired only once. I received numerous answers in thread as well as in my MVP private news group. Now, let us discuss the answer for the same. The answer is – It happens because multiple SQL Server services are running as well as intellisense is turned on. Blog post demonstrates how we can do the same with the help of SQL scripts. Management Studio New Features I have selected my favorite 5 features and blogged about it. IntelliSense for Query Editing Multi Server Query Query Editor Regions Object Explorer Enhancements Activity Monitors Maximum Number of Index per Table One of the questions I asked in my user group was – What is the maximum number of Index per table? I received lots of answers to this question but only two answers are correct. Let us now take a look at them in this blog post. 2010 Default Statistics on Column – Automatic Statistics on Column The truth is, Statistics can be in a table even though there is no Index in it. If you have the auto- create and/or auto-update Statistics feature turned on for SQL Server database, Statistics will be automatically created on the Column based on a few conditions. Please read my previously posted article, SQL SERVER – When are Statistics Updated – What triggers Statistics to Update, for the specific conditions when Statistics is updated. 2011 T-SQL Scripts to Find Maximum between Two Numbers In this blog post there are two different scripts listed which demonstrates way to find the maximum number between two numbers. I need your help, which one of the script do you think is the most accurate way to find maximum number? Find Details for Statistics of Whole Database – DMV – T-SQL Script I was recently asked is there a single script which can provide all the necessary details about statistics for any database. This question made me write following script. I was initially planning to use sp_helpstats command but I remembered that this is marked to be deprecated in future. 2012 Introduction to Function SIGN SIGN Function is very fundamental function. It will return the value 1, -1 or 0. If your value is negative it will return you negative -1 and if it is positive it will return you positive +1. Let us start with a simple small example. Template Browser – A Very Important and Useful Feature of SSMS Templates are like a quick cheat sheet or quick reference. Templates are available to create objects like databases, tables, views, indexes, stored procedures, triggers, statistics, and functions. Templates are also available for Analysis Services as well. The template scripts contain parameters to help you customize the code. You can Replace Template Parameters dialog box to insert values into the script. An invalid floating point operation occurred If you run any of the above functions they will give you an error related to invalid floating point. Honestly there is no workaround except passing the function appropriate values. SQRT of a negative number will give you result in real numbers which is not supported at this point of time as well LOG of a negative number is not possible (because logarithm is the inverse function of an exponential function and the exponential function is NEVER negative). Validating Spatial Object with IsValidDetailed Function SQL Server 2012 has introduced the new function IsValidDetailed(). This function has made my life very easy. In simple words, this function will check if the spatial object passed is valid or not. If it is valid it will give information that it is valid. If the spatial object is not valid it will return the answer that it is not valid and the reason for the same. This makes it very easy to debug the issue and make the necessary correction. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Weekly Series – Memory Lane – #034

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 UDF – User Defined Function to Strip HTML – Parse HTML – No Regular Expression The UDF used in the blog does fantastic task – it scans entire HTML text and removes all the HTML tags. It keeps only valid text data without HTML task. This is one of the quite commonly requested tasks many developers have to face everyday. De-fragmentation of Database at Operating System to Improve Performance Operating system skips MDF file while defragging the entire filesystem of the operating system. It is absolutely fine and there is no impact of the same on performance. Read the entire blog post for my conversation with our network engineers. Delay Function – WAITFOR clause – Delay Execution of Commands How do you delay execution of the commands in SQL Server – ofcourse by using WAITFOR keyword. In this blog post, I explain the same with the help of T-SQL script. Find Length of Text Field To measure the length of TEXT fields the function is DATALENGTH(textfield). Len will not work for text field. As of SQL Server 2005, developers should migrate all the text fields to VARCHAR(MAX) as that is the way forward. Retrieve Current Date Time in SQL Server CURRENT_TIMESTAMP, GETDATE(), {fn NOW()} There are three ways to retrieve the current datetime in SQL SERVER. CURRENT_TIMESTAMP, GETDATE(), {fn NOW()} Explanation and Comparison of NULLIF and ISNULL An interesting observation is NULLIF returns null if it comparison is successful, whereas ISNULL returns not null if its comparison is successful. In one way they are opposite to each other. Here is my question to you - How to create infinite loop using NULLIF and ISNULL? If this is even possible? 2008 Introduction to SERVERPROPERTY and example SERVERPROPERTY is a very interesting system function. It returns many of the system values. I use it very frequently to get different server values like Server Collation, Server Name etc. SQL Server Start Time We can use DMV to find out what is the start time of SQL Server in 2008 and later version. In this blog you can see how you can do the same. Find Current Identity of Table Many times we need to know what is the current identity of the column. I have found one of my developers using aggregated function MAX () to find the current identity. However, I prefer following DBCC command to figure out current identity. Create Check Constraint on Column Some time we just need to create a simple constraint over the table but I have noticed that developers do many different things to make table column follow rules than just creating constraint. I suggest constraint is a very useful concept and every SQL Developer should pay good attention to this subject. 2009 List Schema Name and Table Name for Database This is one of the blog post where I straight forward display script. One of the kind of blog posts, which I still love to read and write. Clustered Index on Separate Drive From Table Location A table devoid of primary key index is called heap, and here data is not arranged in a particular order, which gives rise to issues that adversely affect performance. Data must be stored in some kind of order. If we put clustered index on it then the order will be forced by that index and the data will be stored in that particular order. Understanding Table Hints with Examples Hints are options and strong suggestions specified for enforcement by the SQL Server query processor on DML statements. The hints override any execution plan the query optimizer might select for a query. 2010 Data Pages in Buffer Pool – Data Stored in Memory Cache One of my earlier year article, which I still read it many times and point developers to read it again. It is clear from the Resultset that when more than one index is used, datapages related to both or all of the indexes are stored in Memory Cache separately. TRANSACTION, DML and Schema Locks Can you create a situation where you can see Schema Lock? Well, this is a very simple question, however during the interview I notice over 50 candidates failed to come up with the scenario. In this blog post, I have demonstrated the situation where we can see the schema lock in database. 2011 Solution – Puzzle – Statistics are not updated but are Created Once In this example I have created following situation: Create Table Insert 1000 Records Check the Statistics Now insert 10 times more 10,000 indexes Check the Statistics – it will be NOT updated Auto Update Statistics and Auto Create Statistics for database is TRUE Now I have requested two things in the example 1) Why this is happening? 2) How to fix this issue? Selecting Domain from Email Address This is a straight to script blog post where I explain how to select only domain name from entire email address. Solution – Generating Zero Without using Any Numbers in T-SQL How to get zero digit without using any digit? This is indeed a very interesting question and the answer is even interesting. Try to come up with answer in next 10 minutes and if you can’t come up with the answer the blog post read this post for solution. 2012 Simple Explanation and Puzzle with SOUNDEX Function and DIFFERENCE Function In simple words - SOUNDEX converts an alphanumeric string to a four-character code to find similar-sounding words or names. DIFFERENCE function returns an integer value. The  integer returned is the number of characters in the SOUNDEX values that are the same. Read Only Files and SQL Server Management Studio (SSMS) I have come across a very interesting feature in SSMS related to “Read Only” files. I believe it is a little unknown feature as well so decided to write a blog about the same. Identifying Column Data Type of uniqueidentifier without Querying System Tables 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 the table name and you are allowed to return any kind of error if the table does not have uniqueidentifier column. Read the blog post to find the answer. Solution – User Not Able to See Any User Created Object in Tables – Security and Permissions Issue Interesting question – “When I try to connect to SQL Server, it lets me connect just fine as well let me open and explore the database. I noticed that I do not see any user created instances but when my colleague attempts to connect to the server, he is able to explore the database as well see all the user created tables and other objects. Can you help me fix it?” Importing CSV File Into Database – SQL in Sixty Seconds #018 – Video Here is interesting small 60 second video on how to import CSV file into Database. ColumnStore Index – Batch Mode vs Row Mode Here is the logic behind when Columnstore Index uses Batch Mode and when it uses Row Mode. A batch typically represents about 1000 rows of data. Batch mode processing also uses algorithms that are optimized for the multicore CPUs and increased memory throughput. Follow up – Usage of $rowguid and $IDENTITY This is an excellent follow up blog post of my earlier blog post where I explain where to use $rowguid and $identity.  If you do not know the difference between them, this is a blog with a script example. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • How do I construct a Django reverse/url using query args?

    - by Andrew Dalke
    I have URLs like http://example.com/depict?smiles=CO&width=200&height=200 (and with several other optional arguments) My urls.py contains: urlpatterns = patterns('', (r'^$', 'cansmi.index'), (r'^cansmi$', 'cansmi.cansmi'), url(r'^depict$', cyclops.django.depict, name="cyclops-depict"), I can go to that URL and get the 200x200 PNG that was constructed, so I know that part works. In my template from the "cansmi.cansmi" response I want to construct a URL for the named template "cyclops-depict" given some query parameters. I thought I could do {% url cyclops-depict smiles=input_smiles width=200 height=200 %} where "input_smiles" is an input to the template via a form submission. In this case it's the string "CO" and I thought it would create a URL like the one at top. This template fails with a TemplateSyntaxError: Caught an exception while rendering: Reverse for 'cyclops-depict' with arguments '()' and keyword arguments '{'smiles': u'CO', 'height': 200, 'width': 200}' not found. This is a rather common error message both here on StackOverflow and elsewhere. In every case I found, people were using them with parameters in the URL path regexp, which is not the case I have where the parameters go into the query. That means I'm doing it wrong. How do I do it right? That is, I want to construct the full URL, including path and query parameters, using something in the template. For reference, % python manage.py shell Python 2.6.1 (r261:67515, Feb 11 2010, 00:51:29) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> from django.core.urlresolvers import reverse >>> reverse("cyclops-depict", kwargs=dict()) '/depict' >>> reverse("cyclops-depict", kwargs=dict(smiles="CO")) Traceback (most recent call last): File "<console>", line 1, in <module> File "/Library/Python/2.6/site-packages/django/core/urlresolvers.py", line 356, in reverse *args, **kwargs))) File "/Library/Python/2.6/site-packages/django/core/urlresolvers.py", line 302, in reverse "arguments '%s' not found." % (lookup_view_s, args, kwargs)) NoReverseMatch: Reverse for 'cyclops-depict' with arguments '()' and keyword arguments '{'smiles': 'CO'}' not found.

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  • How to add a column via a query which counts the total rows with a specific criteria in a table with circular relationship in MS ACCESS 2007

    - by Xaqron
    I have a simple table "Employees" with this fields: ID, ParentID, Name ParentID is Nullable since an employee may have no Manager. This table has a one-to-many relationship with itself: ID --one--to--many--> ParentID Now I want a query which returns this columns: Name, Count of rows where their ParentID equals to the current row ID (the row is the manager of that rows) Sample Table: ID | ParentID | Name ====================== 1 | 0 | John ---------------------- 2 | 1 | Bob ---------------------- 3 | 1 | Alice ---------------------- 4 | 3 | Jack This way I can find an employee is the manager of how many other employees. The result should be something like this: Name | Count of Employees ========================== John | 2 -------------- Bob | 0 -------------- Alice | 1 -------------- Jack | 0 How can I achieve this in MS ACCESS 2007? * I have tried built-in query builder without any success.

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  • Is there a way to optimize this update query?

    - by SchlaWiener
    I have a master table called "parent" and a related table called "childs" Now I run a query against the master table to update some values with the sum from the child table like this. UPDATE master m SET quantity1 = (SELECT SUM(quantity1) FROM childs c WHERE c.master_id = m.id), quantity2 = (SELECT SUM(quantity2) FROM childs c WHERE c.master_id = m.id), count = (SELECT COUNT(*) FROM childs c WHERE c.master_id = m.id) WHERE master_id = 666; Which works as expected but is not a good style because I basically make multiple SELECT querys on the same result. Is there a way to optimize that? (Making a query first and storing the values is not an option. I tried this: UPDATE master m SET (quantity1, quantity2, count) = ( SELECT SUM(quantity1), SUM(quantity2), COUNT(*) FROM childs c WHERE c.master_id = m.id ) WHERE master_id = 666; but that doesn't work.

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  • How can I build my SQL query from these tables?

    - by vee
    Hi All, I'm thinking of building query from these 2 tables (on SQL Server 2008). I have 2 tables as shown below: Table 1 MemberId . MemberName . Percentage . Amount1 00000001 AAA 1.0 100 00000002 BBB 1.2 800 00000003 ZZZ 1.0 700 Table 2 MemberId . MemberName . Percentage . Amount2 00000002 BBB 1.5 500 00000002 BBB 1.6 100 00000002 BBB 1.6 150 The result I want is MemberId . MemberName . Percentage . Amount . NettAmount 00000001 AAA 1.0 100 100 00000002 BBB 1.2 800 50 <-- 800-(500+100+150) 00000002 BBB 1.5 500 500 00000002 BBB 1.6 650 650 00000003 ZZZ 1.0 700 700 50 comes from 800 in Table1 minus sum of Amount2 in table2 for MemberID=00000002 Plz someone help me to build the query to reach this result. Thank you in advance.

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  • How do I increase Relevance value in an advanced MySQL query?

    - by morgant
    I've got a MySQL query similar to the following: SELECT *, MATCH (`Description`) AGAINST ('+ipod +touch ' IN BOOLEAN MODE) * 8 + MATCH(`Description`) AGAINST ('ipod touch' IN BOOLEAN MODE) AS Relevance FROM products WHERE ( MATCH (`Description`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) OR MATCH(`LongDescription`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) ) HAVING Relevance > 1 ORDER BY Relevance DESC Now, I've made the query more advanced by also searching for UPC: SELECT *, MATCH (`Description`) AGAINST ('+ipod +touch ' IN BOOLEAN MODE) * 8 + MATCH(`Description`) AGAINST ('ipod touch' IN BOOLEAN MODE) + `UPC` = '123456789012' * 16 AS Relevance FROM products WHERE ( MATCH (`Description`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) OR MATCH(`LongDescription`) AGAINST ('+ipod +touch' IN BOOLEAN MODE) ) AND `UPC` = '123456789012' HAVING Relevance > 1 ORDER BY Relevance DESC That'll return results, but the fact that I had a successful match on the UPC does not increase the value of Relevance. Can I only do that kind of calculation w/full text searches like MATCH() AGAINST()? Clarification: Okay, so my real question is, why does the following not have a Relevance = 16? SELECT `UPC`, `UPC` = '123456789012' * 16 AS Relevance FROM products WHERE `UPC` = '123456789012' HAVING Relevance > 1 ORDER BY Relevance DESC

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  • When using Query Syntax in C# "Enumeration yielded no results". How to retrieve output

    - by Shantanu Gupta
    I have created this query to fetch some result from database. Here is my table structure. What exaclty is happening. DtMapGuestDepartment as Table 1 DtDepartment as Table 2 Are being used var dept_list= from map in DtMapGuestDepartment.AsEnumerable() where map.Field<Nullable<long>>("GUEST_ID") == DRowGuestPI.Field<Nullable<long>>("PK_GUEST_ID") join dept in DtDepartment.AsEnumerable() on map.Field<Nullable<long>>("DEPARTMENT_ID") equals dept.Field<Nullable<long>>("DEPARTMENT_ID") select dept.Field<string>("DEPARTMENT_ID"); I am performing this query on DataTables and expect it to return me a datatable. Here I want to select distinct department from Table 1 as well which will be my next quest. Please answer to that also if possible.

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  • How can I write a MySQL query to check multiple rows?

    - by Matt
    I have a MySQL table containing data on product features: feature_id feature_product_id feature_finder_id feature_text feature_status_yn 1 1 1 Webcam y 2 1 1 Speakers y 3 1 1 Bluray n I want to write a MySQL query that allows me to search for all products that have a 'y' feature_status_yn value for a given feature_product_id and return the feature_product_id. The aim is to use this as a search tool to allow me to filter results to product IDs only matching the requested feature set. A query of SELECT feature_id FROM product_features WHERE feature_finder_id = '1' AND feature_status_yn = 'y' will return all of the features of a given product. But how can I select all products (feature_product_id) that have a 'y' value when they are on separate lines? Multiple queries might be one way to do it, but I'm wondering whether there's a more elegant solution based purely in SQL.

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  • Is there a library / tool to query MySQL data files (MyISAM / InnoDB) without the server? (the SQLit

    - by MGW
    Oftentimes I want to query my MySQL data directly without a server running or without having access to the server (but having read / write rights to the files). Is there a tool or maybe even a library around to query MySQL data files like it is possible with SQLite? I'm specifically looking for InnoDB and MyISAM support. Performance is not a factor. I don't have any knowledge about MySQL internals, but I presume it should be possible to do and not too hard to get the specific code out? Thank you for any suggestions!

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  • How can I update a field in a MySQL database table by addition in MySQL database in a single query

    - by undefined
    I have a table that stores a value that will be added to over time. When I want to add to the value I would like to do so in a single query rather than - Get oldValue from database newValue = oldValue + X update row with newValue $query1 = "SELECT value FROM table WHERE id = thisID"; $result1 = mysql_query($query1); while($row=mysql_fetch_array($result)) { $oldValue = $row['value']; } $newValue = $oldValue + x $query1 = "UPDATE table SET value = $newValue WHERE id = thisID"; Can this be done in a single query?

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  • How to return null value if the query has no corresponding value?

    - by Holicreature
    Hi i've a query select c.name as companyname, u.name,u.email,u.role,a.date from useraccount u, company c, audittrial a where u.status='active' and u.companyid=c.id and (u.companyid=a.companyID and a.activity like 'User activated%' and a.email=u.email) order by u.companyid desc limit 10 So if the following part doesnt't satisfy, (u.companyid=a.companyID and a.activity like 'User activated%' and a.email=u.email) no rows will be returned.. but i want to return the result of the following query select c.name as companyname, u.name,u.email,u.role,a.date from useraccount u, company c, audittrial a where u.status='active' and u.companyid=c.id order by u.companyid desc limit 10 but to add that, i should return the date if available and return null value if date is not available.. how can i do this?

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  • How to create a MySQL query for time based elements with a 'safe window'?

    - by pj4533
    I am no SQL expert, far from it. I am writing a Rails application, and I am new at that as well. I come from a desktop programming background. My application has a table of data, one of the columns is the time at which the data was logged. I want to create a query with a 'safe window' around EACH row. By that I mean, it returns the first row, then for X minutes (based on the timelogged column) it won't return any data, once X minutes is up, it will return the next row. For example: ID | TimeLogged 1 | 3/5/2010 12:01:01 2 | 3/5/2010 12:01:50 3 | 3/5/2010 12:02:03 4 | 3/5/2010 12:10:30 5 | 3/5/2010 01:30:03 6 | 3/5/2010 01:31:05 With a 'safe window' of 5 minutes I want to create a query to return: 1 | 3/5/2010 12:01:01 4 | 3/5/2010 12:10:30 5 | 3/5/2010 01:30:03 (It skipped the 12:01:50 and 12:02:03 items because they occurred within 5 minutes of the first item.) Another example, with a 'safe window' of 15 minutes I want to return: 1 | 3/5/2010 12:01:01 5 | 3/5/2010 01:30:03 Perhaps I have to just return all data and parse it myself?

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  • Write a SQL Query to replace values and include all the Dates.

    - by VJ
    Well I have this - Table DimDate- Date Table Employee- Id,Name,Points,Date Now the Employee table has points for everyday unless they did not come...so the Date does not have all the Dates entries... I mean for e.g in a week he did not come for 2 days the Employee table has only 5 rows...so I have this dimdate table which has all the dates till 2050 which I want to join with and add Zeros for the dates he does not have points. So I have written this query but does not work - Select E.EmployeeId,D.Date,isNull(E.Points,0) from DimDate D left join Employee E on D.Date between '01-01-2009'and '06-01-2009' where E.EmployeeId=1 The above query give multiple dates and I tried group by on Date but does not work.

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  • SQL grouping query question; evaluating a group of rows based on the value of one field.

    - by user324575
    I've got table vendorparts that lists all my parts and their vendor(s). Parts with multiple vendors have multiple records in this table. I'm trying to write a query that only returns the partid, and vendor of parts that do not have a default vendor assigned. Partid Vendor Defaultflag 1 A 1 2 B 0 2 C 0 3 D 0 3 E 0 3 F 1 4 G 0 I would like to return the following: Partid Vendor 2 A 2 B 4 G I'm obviously having issues with partid 3 and getting the query to see it as having a default vendor assigned.

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  • SQL SERVER – 3 Challenges for DBA and Smart Solutions

    - by Pinal Dave
    Developer’s life is never easy. DBA’s life is even crazier. DBA’s Life When a developer wakes up in the morning, most of the time have no idea what different challenges they are going to face that day. Of course, most of the developers know the project and roadmap, which they are working on. However, developers have no clue what coding challenges which they are going face for that day. DBA’s life is even crazier. When DBA wakes up in the morning – they often thank that they were not disturbed during the night due to server issues. The very next thing they wish is that they do not want to challenge which they can’t solve for that day. The problems DBA face every single day are mostly unpredictable and they just have to solve them as they come during the day. Though the life of DBA is not always bad. There are always ways and methods how one can overcome various challenges. Let us see three of the challenges and how a DBA can use various tools to overcome them. Challenge #1 Synchronize Data Across Server A Very common challenge DBA receive is that they have to synchronize the data across the servers. If you try to manually write that up, it may take forever to accomplish the task. It is nearly impossible to do the same with the help of the T-SQL. However, thankfully there are tools like dbForge Studio which can save a day and synchronize data across servers. Read my detailed blog post about the same over here: SQL SERVER – Synchronize Data Exclusively with T-SQL. Challenge #2 SQL Report Builder DBA’s are often asked to build reports on the go. It really annoys DBA’s, but hardly people care about it. No matter how busy a DBA is, they are just called upon to build reports on things on very short notice. I personally like to avoid any task which is given to me accidently and personally building report can be boring. I rather spend time with High Availability, disaster recovery, performance tuning rather than building report. I use SQL third party tool when I have to work with SQL Report. Others have extended reporting capabilities. The latter group of products includes the SQL report builder built-in todbForge Studio for SQL Server. I have blogged about this earlier over here: SQL SERVER – SQL Report Builder in dbForge Studio for SQL Server. Challenge #3 Work with the OTHER Database The manager does not understand that MySQL is different from SQL Server and SQL Server is different from Oracle. For them everything is same. In my career hundreds of times I have faced a situation that I am given a database to manage or do some task when their regular DBA is on vacation or leave. When I try to explain I do not understand the underlying the technology, I have been usually told that my manager has trust on me and I can do anything. Honestly, I can’t but I hardly dare to argue. I fall back on the third party tool to manage database when it is not in my comfort zone. For example, I was once given MySQL performance tuning task (at that time I did not know MySQL so well). To simplify search for a problem query let us use MySQL Profiler in dbForge Studio for MySQL. It provides such commands as a Query Profiling Mode and Generate Execution Plan. Here is the blog post discussing about the same: MySQL – Profiler : A Simple and Convenient Tool for Profiling SQL Queries. Well, that’s it! There were many different such occasions when I have been saved by the tool. May be some other day I will write part 2 of this blog post. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL Tagged: Devart, SQL Tool

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  • SQL SERVER – Puzzle – Statistics are not Updated but are Created Once

    - by pinaldave
    After having excellent response to my quiz – Why SELECT * throws an error but SELECT COUNT(*) does not?I have decided to ask another puzzling question to all of you. I am running this test on SQL Server 2008 R2. Here is the quick scenario about my setup. Create Table Insert 1000 Records Check the Statistics Now insert 10 times more 10,000 indexes Check the Statistics – it will be NOT updated Note: Auto Update Statistics and Auto Create Statistics for database is TRUE Expected Result – Statistics should be updated – SQL SERVER – When are Statistics Updated – What triggers Statistics to Update Now the question is why the statistics are not updated? The common answer is – we can update the statistics ourselves using UPDATE STATISTICS TableName WITH FULLSCAN, ALL However, the solution I am looking is where statistics should be updated automatically based on algorithm mentioned here. Now the solution is to ____________________. Vinod Kumar is not allowed to take participate over here as he is the one who has helped me to build this puzzle. I will publish the solution on next week. Please leave a comment and if your comment consist valid answer, I will publish with due credit. Here is the script to reproduce the scenario which I mentioned. -- Execution Plans Difference -- Create Sample Database CREATE DATABASE SampleDB GO USE SampleDB GO -- Create Table CREATE TABLE ExecTable (ID INT, FirstName VARCHAR(100), LastName VARCHAR(100), City VARCHAR(100)) GO -- Insert One Thousand Records -- INSERT 1 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 1000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Display statistics of the table - none listed sp_helpstats N'ExecTable', 'ALL' GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City  = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here -- NOTE: Replace your _WA_Sys with stats from above query DBCC SHOW_STATISTICS('ExecTable', _WA_Sys_00000004_7D78A4E7); GO -------------------------------------------------------------- -- Round 2 -- Insert Ten Thousand Records -- INSERT 2 INSERT INTO ExecTable (ID,FirstName,LastName,City) SELECT TOP 10000 ROW_NUMBER() OVER (ORDER BY a.name) RowID, 'Bob', CASE WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%2 = 1 THEN 'Smith' ELSE 'Brown' END, CASE WHEN ROW_NUMBER() OVER (ORDER BY a.name)%20 = 1 THEN 'New York' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 5 THEN 'San Marino' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 3 THEN 'Los Angeles' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 7 THEN 'La Cinega' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 13 THEN 'San Diego' WHEN  ROW_NUMBER() OVER (ORDER BY a.name)%20 = 17 THEN 'Las Vegas' ELSE 'Houston' END FROM sys.all_objects a CROSS JOIN sys.all_objects b GO -- Select Statement SELECT FirstName, LastName, City FROM ExecTable WHERE City  = 'New York' GO -- Display statistics of the table sp_helpstats N'ExecTable', 'ALL' GO -- Replace your Statistics over here -- NOTE: Replace your _WA_Sys with stats from above query DBCC SHOW_STATISTICS('ExecTable', _WA_Sys_00000004_7D78A4E7); GO -- You will notice that Statistics are still updated with 1000 rows -- Clean up Database DROP TABLE ExecTable GO USE MASTER GO ALTER DATABASE SampleDB SET SINGLE_USER WITH ROLLBACK IMMEDIATE; GO DROP DATABASE SampleDB GO Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics, Statistics

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  • SQL SERVER – Guest Post – Glenn Berry – Wait Type – Day 26 of 28

    - by pinaldave
    Glenn Berry works as a Database Architect at NewsGator Technologies in Denver, CO. He is a SQL Server MVP, and has a whole collection of Microsoft certifications, including MCITP, MCDBA, MCSE, MCSD, MCAD, and MCTS. He is also an Adjunct Faculty member at University College – University of Denver, where he has been teaching since 2000. He is one wonderful blogger and often blogs at here. I am big fan of the Dynamic Management Views (DMV) scripts of Glenn. His script are extremely popular and the reality is that he has inspired me to start this series with his famous DMV which I have mentioned in very first  wait stats blog post (I had forgot to request his permission to re-use the script but when asked later on his whole hearty approved it). Here is is his excellent blog post on this subject of wait stats: Analyzing cumulative wait stats in SQL Server 2005 and above has become a popular and effective technique for diagnosing performance issues and further focusing your troubleshooting and diagnostic  efforts.  Rather than just guessing about what resource(s) that SQL Server is waiting on, you can actually find out by running a relatively simple DMV query. Once you know what resources that SQL Server is spending the most time waiting on, you can run more specific queries that focus on that resource to get a better idea what is causing the problem. I do want to throw out a few caveats about using wait stats as a diagnostic tool. First, they are most useful when your SQL Server instance is experiencing performance problems. If your instance is running well, with no indication of any resource pressure from other sources, then you should not worry that much about what the top wait types are. SQL Server will always be waiting on some resource, but many wait types are quite benign, and can be safely ignored. In spite of this, I quite often see experienced DBAs obsessing over the top wait type, even when their SQL Server instance is running extremely well. Second, I often see DBAs jump to the wrong conclusion based on seeing a particular well-known wait type. A good example is CXPACKET waits. People typically jump to the conclusion that high CXPACKET waits means that they should immediately change their instance-level MADOP setting to 1. This is not always the best solution. You need to consider your workload type, and look carefully for any important “missing” indexes that might be causing the query optimizer to use a parallel plan to compensate for the missing index. In this case, correcting the index problem is usually a better solution than changing MAXDOP, since you are curing the disease rather than just treating the symptom. Finally, you should get in the habit of clearing out your cumulative wait stats with the  DBCC SQLPERF(‘sys.dm_os_wait_stats’, CLEAR); command. This is especially important if you have made an configuration or index changes, or if your workload has changed recently. Otherwise, your cumulative wait stats will be polluted with the old stats from weeks or months ago (since the last time SQL Server was started or the stats were cleared).  If you make a change to your SQL Server instance, or add an index, you should clear out your wait stats, and then wait a while to see what your new top wait stats are. At any rate, enjoy Pinal Dave’s series on Wait Stats. This blog post has been written by Glenn Berry (Twitter | Blog) Read all the post in the Wait Types and Queue series. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, Readers Contribution, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQLAuthority News – Follow up on – Replace a Column Name in Multiple Stored Procedure all together

    - by pinaldave
    Last month I had a fantastic time with lots of puzzles and brain teasers, the amount of participation which I have received on the blog is indeed inspiring to write more. One of the blog post was about how to replace a column name in all the stored procedures. The article had very interesting conversation as a follow up. Please read the original article Replace a Column Name in Multiple Stored Procedure all together before reading this blog further as they are connected. Let us start few of the interesting comments. SQL Server Expert Imran Mohammed had a wonderful first and excellent note. I suggest all of you to read it. Imran stresses on the Data Modelling and Logical as well as Physical Design. Developers must create a logical design and get approval on naming convention, data types, references, constraints, indexes etc. He further suggested that one should not cut steps but must follow all the industry standards and guidelines. Here extended my blog post with following note – “Extending Pinal’s answer, what you can do is go to database properties, all tasks, scripts objects, in scripting wizard select all the stored procedure for which you want to change column name, export the query to a new window and then do find and replace, all in once window and execute the script. But make sure you check what you are replacing, sometimes column names are also used in table names, for ex:Table Name: Product and Column Name: ProductId, ProductName”. Thanks Imran Great Points!  Gatej Alexandru suggested that it is not good idea to DROP or CREATE but rather use ALTER as quite possible there may be permissions issue as well. Very good point let me see if I can write blog post over it. Vinay Kumar and SQLStudent144 have proposed another method to achieve the same. I am combining their solution and writing them here. Step 1. Press Ctrl+T or change “Result to Text” mode. Step 2. Execute below commands.SELECT 'EXEC sp_helptext [' + referencing_schema_name + '.' + referencing_entity_name + ']' FROM sys.dm_sql_referencing_entities('schema.objectname','OBJECT') Where schema.objectname is the object or table you are searching for. Step 3. Now copy the result and paste in new window. Again Press Ctrl+T or change “Result to Text” mode. Step 4. Copy the result and paste in new window. Execute the query. Step 5. Copy the result and paste in new window. Step 6. Now find your searching text in the script, make necessary changes and execute this script. Do not forget to remove the code which is generated in resultset which are not relevant to the T-SQL Script. Digitqr suggest we can do this for other objects besides Stored Procedure as well. Iosif suggests to use tool SQL Search from RedGate. I guess this sums it well. We have an alternative perspective to our original issue of replacing the column name in multiple stored procedure. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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