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  • how to create image thumbnails using django running on jython?

    - by Nitin Garg
    Hi guys, I am a newbee to django and jython. I need to create and save image thumbnails in database. I am using django running on jython and mysql database. I was exploring python imaging library, but the i found out that i wont work with jython. How do i create image thumbnails using jython and then save them in mysql db?? Any kind of help will be appreciated. thanx

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  • How can I access the "through" object of a Django ManyToManyField?

    - by Macha
    I have the following models in my Django app. How can I from the Team model find all the User objects who have accepted as True in the Membership model? I know I need to use Team.objects.filter(), but I'm not sure how to check the value of the accepted field. from django.contrib.auth.models import User class Team(models.Model): members = models.ManyToManyField(User, through="Membership") class Membership(models.Model): user = models.ForeignKey(User) team = models.ForeignKey(Team) accepted = models.BooleanField(default=False)

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  • Unittest in Django. Static variable feeded into the test case

    - by ziang
    I want to generate some dynamic data and feed these data in to test cases. But I found that Django will initial the test class every time to do the test. So the data will get generated every time django test framework calls the function. Is there anyway to use something like the singleton or static variable to solve the problem? What should be the solution? Thanks!

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  • SQL Authority News – Play by Play with Pinal Dave – A Birthday Gift

    - by Pinal Dave
    Today is my birthday. Personal Note When I was young, I was always looking forward to my birthday as on this day, I used to get gifts from everybody. Now when I am getting old on each of my birthday, I have almost same feeling but the direction is different. Now on each of my birthday, I feel like giving gifts to everybody. I have received lots of support, love and respect from everybody; and now I must return it back.Well, on this birthday, I have very unique gifts for everybody – my latest course on SQL Server. How I Tune Performance I often get questions where I am asked how do I work on a normal day. I am often asked that how do I work when I have performance tuning project is assigned to me. Lots of people have expressed their desire that they want me to explain and demonstrate my own method of solving performance problem when I am facing real world problem. It is a pretty difficult task as in the real world, nothing goes as planned and usually planned demonstrations have no place there. The real world, demands real solutions and in a timely fashion. If a consultant goes to industry and does not demonstrate his/her capabilities in very first few minutes, it does not matter how much fame he/she is, the door is shown to them eventually. It is true and in my early career, I have faced it quite commonly. I have learned the trick to be honest from the start and request absolutely transparent communication from the organization where I am to consult. Play by Play Play by Play is a very unique setup. It is not planned and it is a step by step course. It is like a reality show – a very real encounter to the problem and real problem solving approach. I had a great time doing this course. Geoffrey Grosenbach (VP of Pluralsight) sits down with me to see what a SQL Server Admin does in the real world. This Play-by-Play focuses on SQL Server performance tuning and I go over optimizing queries and fine-tuning the server. The table of content of this course is very simple. Introduction In the introduction I explained my basic strategies when I am approached by a customer for performance tuning. Basic Information Gathering In this module I explain how I do gather various information for performance tuning project. It is very crucial to demonstrate to customers for consultant his capability of solving problem. I attempt to resolve a small problem which gives a big positive impact on performance, consultant have to gather proper information from the start. I demonstrate in this module, how one can collect all the important performance tuning metrics. Removing Performance Bottleneck In this module, I build upon the previous module’s statistics collected. I analysis various performance tuning measures and immediately start implementing various tweaks on the performance, which will start improving the performance of my server. This is a very effective method and it gives immediate return of efforts. Index Optimization Indexes are considered as a silver bullet for performance tuning. However, it is not true always there are plenty of examples where indexes even performs worst after implemented. The key is to understand a few of the basic properties of the index and implement the right things at the right time. In this module, I describe in detail how to do index optimizations and what are right and wrong with Index. If you are a DBA or developer, and if your application is running slow – this is must attend module for you. I have some really interesting stories to tell as well. Optimize Query with Rewrite Every problem has more than one solution, in this module we will see another very famous, but hard to master skills for performance tuning – Query Rewrite. There are few do’s and don’ts for any query rewrites. I take a very simple example and demonstrate how query rewrite can improve the performance of the query at many folds. I also share some real world funny stories in this module. This course is hosted at Pluralsight. You will need a valid login for Pluralsight to watch  Play by Play: Pinal Dave course. You can also sign up for FREE Trial of Pluralsight to watch this course. As today is my birthday – I will give 10 people (randomly) who will express their desire to learn this course, a free code. Please leave your comment and I will send you free code to watch this course for free. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority News, T SQL, Video

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  • SQL SERVER – Weekly Series – Memory Lane – #053 – Final Post in Series

    - by Pinal Dave
    It has been a fantastic journey to write memory lane series for an entire year. This series gave me the opportunity to go back and see what I have contributed to this blog throughout the last 7 years. This was indeed fantastic series as this provided me the opportunity to witness how technology has grown throughout the year and how I have progressed in my career while writing this blog post. This series was indeed fantastic experience readers as many joined during the last few years and were not sure what they have missed in recent years. Let us continue with the final episode of the Memory Lane Series. 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 Get Current User – Get Logged In User Here is the straight script which list logged in SQL Server users. Disable All Triggers on a Database – Disable All Triggers on All Servers Question : How to disable all the triggers for a database? Additionally, how to disable all the triggers for all servers? For answer execute the script in the blog post. Importance of Master Database for SQL Server Startup I have received following questions many times. I will list all the questions here and answer them together. What is the purpose of Master database? Should our backup Master database? Which database is must have database for SQL Server for startup? Which are the default system database created when SQL Server 2005 is installed for the first time? What happens if Master database is corrupted? Answers to all of the questions are very much related. 2008 DECLARE Multiple Variables in One Statement SQL Server is a great product and it has many features which are very unique to SQL Server. Regarding feature of SQL Server where multiple variable can be declared in one statement, it is absolutely possible to do. 2009 How to Enable Index – How to Disable Index – Incorrect syntax near ‘ENABLE’ Many times I have seen that the index is disabled when there is a large update operation on the table. Bulk insert of very large file updates in any table using SSIS is usually preceded by disabling the index and followed by enabling the index. I have seen many developers running the following query to disable the index. 2010 List of all the Views from Database Many emails I received suggesting that they have hundreds of the view and now have no clue what is going on and how many of them have indexes and how many does not have an index. Some even asked me if there is any way they can get a list of the views with the property of Index along with it. Here is the quick script which does exactly the same. You can also include many other columns from the same view. Minimum Maximum Memory – Server Memory Options I was recently reading about SQL Server Memory Options over here. While reading this one line really caught my attention is minimum value allowed for maximum memory options. The default setting for min server memory is 0, and the default setting for max server memory is 2147483647. The minimum amount of memory you can specify for max server memory is 16 megabytes (MB). 2011 Fundamentals of Columnstore Index There are two kinds of storage in a database. Row Store and Column Store. Row store does exactly as the name suggests – stores rows of data on a page – and column store stores all the data in a column on the same page. These columns are much easier to search – instead of a query searching all the data in an entire row whether the data are relevant or not, column store queries need only to search a much lesser number of the columns. How to Ignore Columnstore Index Usage in Query In summary the question in simple words “How can we ignore using the column store index in selective queries?” Very interesting question – you can use I can understand there may be the cases when the column store index is not ideal and needs to be ignored the same. You can use the query hint IGNORE_NONCLUSTERED_COLUMNSTORE_INDEX to ignore the column store index. The SQL Server Engine will use any other index which is best after ignoring the column store index. 2012 Storing Variable Values in Temporary Array or Temporary List SQL Server does not support arrays or a dynamic length storage mechanism like list. Absolutely there are some clever workarounds and few extra-ordinary solutions but everybody can;t come up with such solution. Additionally, sometime the requirements are very simple that doing extraordinary coding is not required. Here is the simple case. Move Database Files MDF and LDF to Another Location It is not common to keep the Database on the same location where OS is installed. Usually Database files are in SAN, Separate Disk Array or on SSDs. This is done usually for performance reason and manageability perspective. Now the challenges comes up when database which was installed at not preferred default location and needs to move to a different location. Here is the quick tutorial how you can do it. UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL If your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same result set you can add an additional static column and order by that column. Let us re-create the same scenario. Copy Data from One Table to Another Table – SQL in Sixty Seconds #031 – Video http://www.youtube.com/watch?v=FVWIA-ACMNo 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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  • Setting up a Complete Django E-commerce store in 30 minutes

    <b>Packt:</b> "In order to demonstrate Django's rapid development potential, we will begin by constructing a simple, but fully-featured, e-commerce store. The goal is to be up and running with a product catalog and products for sale, including a simple payment processing interface, in about half-an-hour."

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  • SQL SERVER – CXPACKET – Parallelism – Advanced Solution – Wait Type – Day 7 of 28

    - by pinaldave
    Earlier we discussed about the what is the common solution to solve the issue with CXPACKET wait time. Today I am going to talk about few of the other suggestions which can help to reduce the CXPACKET wait. If you are going to suggest that I should focus on MAXDOP and COST THRESHOLD – I totally agree. I have covered them in details in yesterday’s blog post. Today we are going to discuss few other way CXPACKET can be reduced. Potential Reasons: If data is heavily skewed, there are chances that query optimizer may estimate the correct amount of the data leading to assign fewer thread to query. This can easily lead to uneven workload on threads and may create CXPAKCET wait. While retrieving the data one of the thread face IO, Memory or CPU bottleneck and have to wait to get those resources to execute its tasks, may create CXPACKET wait as well. Data which is retrieved is on different speed IO Subsystem. (This is not common and hardly possible but there are chances). Higher fragmentations in some area of the table can lead less data per page. This may lead to CXPACKET wait. As I said the reasons here mentioned are not the major cause of the CXPACKET wait but any kind of scenario can create the probable wait time. Best Practices to Reduce CXPACKET wait: Refer earlier article regarding MAXDOP and Cost Threshold. De-fragmentation of Index can help as more data can be obtained per page. (Assuming close to 100 fill-factor) If data is on multiple files which are on multiple similar speed physical drive, the CXPACKET wait may reduce. Keep the statistics updated, as this will give better estimate to query optimizer when assigning threads and dividing the data among available threads. Updating statistics can significantly improve the strength of the query optimizer to render proper execution plan. This may overall affect the parallelism process in positive way. Bad Practice: In one of the recent consultancy project, when I was called in I noticed that one of the ‘experienced’ DBA noticed higher CXPACKET wait and to reduce them, he has increased the worker threads. The reality was increasing worker thread has lead to many other issues. With more number of the threads, more amount of memory was used leading memory pressure. As there were more threads CPU scheduler faced higher ‘Context Switching’ leading further degrading performance. When I explained all these to ‘experienced’ DBA he suggested that now we should reduce the number of threads. Not really! Lower number of the threads may create heavy stalling for parallel queries. I suggest NOT to touch the setting of number of the threads when dealing with CXPACKET wait. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and I no way claim it to be accurate. I suggest reading book on-line for further clarification. All the discussion of Wait Stats over here is generic and it varies by system to system. You are recommended to test this on development server before implementing to production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • SQL SERVER – UNION ALL and ORDER BY – How to Order Table Separately While Using UNION ALL

    - by pinaldave
    I often see developers trying following syntax while using ORDER BY. SELECT Columns FROM TABLE1 ORDER BY Columns UNION ALL SELECT Columns FROM TABLE2 ORDER BY Columns However the above query will return following error. Msg 156, Level 15, State 1, Line 5 Incorrect syntax near the keyword ‘ORDER’. It is not possible to use two different ORDER BY in the UNION statement. UNION returns single resultsetand as per the Logical Query Processing Phases. However, if your requirement is such that you want your top and bottom query of the UNION resultset independently sorted but in the same resultset you can add an additional static column and order by that column. Let us re-create the same scenario. First create two tables and populated with sample data. USE tempdb GO -- Create table CREATE TABLE t1 (ID INT, Col1 VARCHAR(100)); CREATE TABLE t2 (ID INT, Col1 VARCHAR(100)); GO -- Sample Data Build INSERT INTO t1 (ID, Col1) SELECT 1, 'Col1-t1' UNION ALL SELECT 2, 'Col2-t1' UNION ALL SELECT 3, 'Col3-t1'; INSERT INTO t2 (ID, Col1) SELECT 3, 'Col1-t2' UNION ALL SELECT 2, 'Col2-t2' UNION ALL SELECT 1, 'Col3-t2'; GO If we SELECT the data from both the table using UNION ALL . -- SELECT without ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 GO We will get the data in following order. However, our requirement is to get data in following order. If we need data ordered by Column1 we can ORDER the resultset ordered by Column1. -- SELECT with ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 ORDER BY ID GO Now to get the data in independently sorted in UNION ALL let us add additional column OrderKey and use ORDER BY  on that column. I think the description does not do proper justice let us see the example here. -- SELECT with ORDER BY - with ORDER KEY SELECT ID, Col1, 'id1' OrderKey FROM t1 UNION ALL SELECT ID, Col1, 'id2' OrderKey FROM t2 ORDER BY OrderKey, ID GO The above query will give the desired result. Now do not forget to clean up the database by running the following script. -- Clean up DROP TABLE t1; DROP TABLE t2; GO Here is the complete script used in this example. USE tempdb GO -- Create table CREATE TABLE t1 (ID INT, Col1 VARCHAR(100)); CREATE TABLE t2 (ID INT, Col1 VARCHAR(100)); GO -- Sample Data Build INSERT INTO t1 (ID, Col1) SELECT 1, 'Col1-t1' UNION ALL SELECT 2, 'Col2-t1' UNION ALL SELECT 3, 'Col3-t1'; INSERT INTO t2 (ID, Col1) SELECT 3, 'Col1-t2' UNION ALL SELECT 2, 'Col2-t2' UNION ALL SELECT 1, 'Col3-t2'; GO -- SELECT without ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 GO -- SELECT with ORDER BY SELECT ID, Col1 FROM t1 UNION ALL SELECT ID, Col1 FROM t2 ORDER BY ID GO -- SELECT with ORDER BY - with ORDER KEY SELECT ID, Col1, 'id1' OrderKey FROM t1 UNION ALL SELECT ID, Col1, 'id2' OrderKey FROM t2 ORDER BY OrderKey, ID GO -- Clean up DROP TABLE t1; DROP TABLE t2; GO I am sure there are many more ways to achieve this, what method would you use if you have to face the similar situation? Reference: Pinal Dave (http://blog.sqlauthority.com)   Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Big Data – Data Mining with Hive – What is Hive? – What is HiveQL (HQL)? – Day 15 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned the importance of the operational database in Big Data Story. In this article we will understand what is Hive and HQL in Big Data Story. Yahoo started working on PIG (we will understand that in the next blog post) for their application deployment on Hadoop. The goal of Yahoo to manage their unstructured data. Similarly Facebook started deploying their warehouse solutions on Hadoop which has resulted in HIVE. The reason for going with HIVE is because the traditional warehousing solutions are getting very expensive. What is HIVE? Hive is a datawarehouseing infrastructure for Hadoop. The primary responsibility is to provide data summarization, query and analysis. It  supports analysis of large datasets stored in Hadoop’s HDFS as well as on the Amazon S3 filesystem. The best part of HIVE is that it supports SQL-Like access to structured data which is known as HiveQL (or HQL) as well as big data analysis with the help of MapReduce. Hive is not built to get a quick response to queries but it it is built for data mining applications. Data mining applications can take from several minutes to several hours to analysis the data and HIVE is primarily used there. HIVE Organization The data are organized in three different formats in HIVE. Tables: They are very similar to RDBMS tables and contains rows and tables. Hive is just layered over the Hadoop File System (HDFS), hence tables are directly mapped to directories of the filesystems. It also supports tables stored in other native file systems. Partitions: Hive tables can have more than one partition. They are mapped to subdirectories and file systems as well. Buckets: In Hive data may be divided into buckets. Buckets are stored as files in partition in the underlying file system. Hive also has metastore which stores all the metadata. It is a relational database containing various information related to Hive Schema (column types, owners, key-value data, statistics etc.). We can use MySQL database over here. What is HiveSQL (HQL)? Hive query language provides the basic SQL like operations. Here are few of the tasks which HQL can do easily. Create and manage tables and partitions Support various Relational, Arithmetic and Logical Operators Evaluate functions Download the contents of a table to a local directory or result of queries to HDFS directory Here is the example of the HQL Query: SELECT upper(name), salesprice FROM sales; SELECT category, count(1) FROM products GROUP BY category; When you look at the above query, you can see they are very similar to SQL like queries. Tomorrow In tomorrow’s blog post we will discuss about very important components of the Big Data Ecosystem – Pig. 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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  • Whether to use UNION or OR in SQL Server Queries

    - by Dinesh Asanka
    Recently I came across with an article on DB2 about using Union instead of OR. So I thought of carrying out a research on SQL Server on what scenarios UNION is optimal in and which scenarios OR would be best. I will analyze this with a few scenarios using samples taken  from the AdventureWorks database Sales.SalesOrderDetail table. Scenario 1: Selecting all columns So we are going to select all columns and you have a non-clustered index on the ProductID column. --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR ProductID =709 OR ProductID =998 OR ProductID =875 OR ProductID =976 OR ProductID =874 --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 709 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 998 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 875 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 976 UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 874 So query 1 is using OR and the later is using UNION. Let us analyze the execution plans for these queries. Query 1 Query 2 As expected Query 1 will use Clustered Index Scan but Query 2, uses all sorts of things. In this case, since it is using multiple CPUs you might have CX_PACKET waits as well. Let’s look at the profiler results for these two queries: CPU Reads Duration Row Counts OR 78 1252 389 3854 UNION 250 7495 660 3854 You can see from the above table the UNION query is not performing well as the  OR query though both are retuning same no of rows (3854).These results indicate that, for the above scenario UNION should be used. Scenario 2: Non-Clustered and Clustered Index Columns only --Query 1 : OR SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR ProductID =709 OR ProductID =998 OR ProductID =875 OR ProductID =976 OR ProductID =874 GO --Query 2 : UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 709 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 998 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 875 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 976 UNION SELECT ProductID,SalesOrderID, SalesOrderDetailID FROM Sales.SalesOrderDetail WHERE ProductID = 874 GO So this time, we will be selecting only index columns, which means these queries will avoid a data page lookup. As in the previous case we will analyze the execution plans: Query 1 Query 2 Again, Query 2 is more complex than Query 1. Let us look at the profile analysis: CPU Reads Duration Row Counts OR 0 24 208 3854 UNION 0 38 193 3854 In this analyzis, there is only slight difference between OR and UNION. Scenario 3: Selecting all columns for different fields Up to now, we were using only one column (ProductID) in the where clause.  What if we have two columns for where clauses and let us assume both are covered by non-clustered indexes? --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR CarrierTrackingNumber LIKE 'D0B8%' --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE CarrierTrackingNumber  LIKE 'D0B8%' Query 1 Query 2: As we can see, the query plan for the second query has improved. Let us see the profiler results. CPU Reads Duration Row Counts OR 47 1278 443 1228 UNION 31 1334 400 1228 So in this case too, there is little difference between OR and UNION. Scenario 4: Selecting Clustered index columns for different fields Now let us go only with clustered indexes: --Query 1 : OR SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 OR CarrierTrackingNumber LIKE 'D0B8%' --Query 2 : UNION SELECT * FROM Sales.SalesOrderDetail WHERE ProductID = 714 UNION SELECT * FROM Sales.SalesOrderDetail WHERE CarrierTrackingNumber  LIKE 'D0B8%' Query 1 Query 2 Now both execution plans are almost identical except is an additional Stream Aggregate is used in the first query. This means UNION has advantage over OR in this scenario. Let us see profiler results for these queries again. CPU Reads Duration Row Counts OR 0 319 366 1228 UNION 0 50 193 1228 Now see the differences, in this scenario UNION has somewhat of an advantage over OR. Conclusion Using UNION or OR depends on the scenario you are faced with. So you need to do your analyzing before selecting the appropriate method. Also, above the four scenarios are not all an exhaustive list of scenarios, I selected those for the broad description purposes only.

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  • SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY

    - by pinaldave
    Some time an interesting feature and smart audience makes total difference at places. From last two days, I have been writing on SQL Server 2012 feature FIRST_VALUE and LAST_VALUE. Please read following post before I continue today as this question is based on the same. Introduction to FIRST_VALUE and LAST_VALUE Introduction to FIRST_VALUE and LAST_VALUE with OVER clause As a comment of the second post I received excellent question from Nilesh Molankar. He asks what will happen if we change few things in the T-SQL. I really like this question as this kind of questions will make us sharp and help us perform in critical situation in need. We recently publish SQL Server Interview Questions book. I promise that in future version of this book, we will for sure include this question. Instead of repeating his question, I am going to ask something very similar to his question. Let us first run following query (read yesterday’s blog post for more detail): USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Here is the resultset of the above query. Now let us change the ORDER BY clause of OVER clause in above query and see what is the new result. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Now let us see the result and ready for interesting question: Puzzle You can see that row number 2, 3, 4, and 5 has same SalesOrderID = 43667. The FIRST_VALUE is 78 and LAST_VALUE is 77. Now if these function was working on maximum and minimum value they should have given answer as 77 and 80 respectively instead of 78 and 77. Also the value of FIRST_VALUE is greater than LAST_VALUE 77. Why? Explain in detail. Hint Let me give you a simple hint. Just for simplicity I have changed the order of columns selected in the SELECT and ORDER BY (at the end). This will not change resultset but just order of the columns as well order of the rows. However, the data remains the same. USE AdventureWorks GO SELECT s.OrderQty,s.SalesOrderID,s.SalesOrderDetailID, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY OrderQty ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.OrderQty,s.SalesOrderID,s.SalesOrderDetailID GO Above query returns following result: Now I am very sure all of you have figured out the solution. Here is the second hint – pay attention to row 2, 3, 4, and 10. Hint2 T-SQL Enhancements: FIRST_VALUE() and LAST_VALUE() MSDN: FIRST_VALUE and LAST_VALUE Rules Leave a comment with your detailed answer by Nov 15′s blog post. Open world-wide (where Amazon ships books) If you blog about puzzle’s solution and if you win, you win additional surprise gift as well. Prizes Print copy of my new book SQL Server Interview Questions Amazon|Flipkart If you already have this book, you can opt for any of my other books SQL Wait Stats [Amazon|Flipkart|Kindle] and SQL Programming [Amazon|Flipkart|Kindle]. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Django doesn't refresh my request object when reloading the current page.

    - by Boris Rusev
    I have a Django web site which I want ot be viewable in different languages. Until this morning everything was working fine. Here is the deal. I go to my say About Us page and it is in English. Below it there is the change language button and when I press it everything "magically" translates to Bulgarian just the way I want it. On the other hand I have a JS menu from which the user is able to browse through the products. I click on 'T-Shirt' then a sub-menu opens bellow the previously pressed containing different categories - Men, Women, Children. The link guides me to a page where the exact clothes I have requested are listed. BUT... When I try to change the language THEN, nothing happens. I go to the Abouts Page, change the language from there, return to the clothes catalog and the language is changed... I will no paste some code. This is my change button code: function changeLanguage() { if (getCookie('language') == 'EN') { setCookie("language", 'BG'); } else { setCookie("language", 'EN'); } window.location.reload(); } These are my URL patterns: urlpatterns = patterns('', # Example: # (r'^enter_clothing/', include('enter_clothing.foo.urls')), # Uncomment the admin/doc line below and add 'django.contrib.admindocs' # to INSTALLED_APPS to enable admin documentation: # (r'^admin/doc/', include('django.contrib.admindocs.urls')), # Uncomment the next line to enable the admin: (r'^site_media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': '/home/boris/Projects/enter_clothing/templates/media', 'show_indexes': True}), (r'^$', 'enter_clothing.clothes_app.views.index'), (r'^home', 'enter_clothing.clothes_app.views.home'), (r'^products', 'enter_clothing.clothes_app.views.products'), (r'^orders', 'enter_clothing.clothes_app.views.orders'), (r'^aboutUs', 'enter_clothing.clothes_app.views.aboutUs'), (r'^contactUs', 'enter_clothing.clothes_app.views.contactUs'), (r'^admin/', include(admin.site.urls)), (r'^(\w+)/(\w+)/page=(\d+)', 'enter_clothing.clothes_app.views.displayClothes'), ) My About Us page: @base def aboutUs(request): return """<b>%s</b>""" % getTranslation("About Us Text", request.COOKIES['language']) The @base method: def base(myfunc): def inner_func(*args, **kwargs): try: args[0].COOKIES['language'] except: args[0].COOKIES['language'] = 'BG' resetGlobalVariables() initCollections(args[0]) categoriesByCollection = dict((collection, getCategoriesFromCollection(args[0], collection)) for collection in collections) if args[0].COOKIES['language'] == 'BG': for k, v in categoriesByCollection.iteritems(): categoriesByCollection[k] = reduce(lambda a,b: a+b, map(lambda x: """<li><a href="/%s/%s/page=1">%s</a></li>""" % (translateCategory(args[0], x), translateCollection(args[0], k), str(x)), v), "") else: for k, v in categoriesByCollection.iteritems(): categoriesByCollection[k] = reduce(lambda a,b: a+b, map(lambda x: """<li><a href="/%s/%s/page=1">%s</a></li>""" % (str(x), str(k), str(x)), v), "") contents = myfunc(*args, **kwargs) return render_to_response('index.html', {'title': title, 'categoriesByCollection': categoriesByCollection.iteritems(), 'keys': enumerate(keys), 'values': enumerate(values), 'contents': contents, 'btnHome':getTranslation("Home Button", args[0].COOKIES['language']), 'btnProducts':getTranslation("Products Button", args[0].COOKIES['language']), 'btnOrders':getTranslation("Orders Button", args[0].COOKIES['language']), 'btnAboutUs':getTranslation("About Us Button", args[0].COOKIES['language']), 'btnContacts':getTranslation("Contact Us Button", args[0].COOKIES['language']), 'btnChangeLanguage':getTranslation("Button Change Language", args[0].COOKIES['language'])}) return inner_func And the catalog page: @base def displayClothes(request, category, collection, page): clothesToDisplay = getClothesFromCollectionAndCategory(request, category, collection) contents = "" pageCount = len(clothesToDisplay) / ( rowCount * columnCount) + 1 matrixSize = rowCount * columnCount currentPage = str(page).replace("page=", "") currentPage = int(currentPage) - 1 #raise Exception(request) # this is for the clothes layout for x in range(currentPage * matrixSize, matrixSize * (currentPage + 1)): if x < len(clothesToDisplay): if request.COOKIES['language'] == 'EN': contents += """<div class="clothes">%s</div>""" % clothesToDisplay[x].getEnglishHTML() else: contents += """<div class="clothes">%s</div>""" % clothesToDisplay[x].getBulgarianHTML() if (x + 1) % columnCount == 0: contents += """<div class="clear"></div>""" contents += """<div class="clear"></div>""" # this is for the page links if pageCount > 1: for x in range(0, pageCount): if x == currentPage: contents += """<a href="/%s/%s/page=%s"><span style="font-size: 20pt; color: black;">%s</span></a>""" % (category, collection, x + 1, x + 1) else: contents += """<a href="/%s/%s/page=%s"><span style="font-size: 20pt; color: blue;">%s</span></a>""" % (category, collection, x + 1, x + 1) return """%s""" % (contents) Let me explain that you needn't be alarmed by the large quantities of code I have posted. You don't have to understand it or even look at all of it. I've published it just in case because I really can't understand the origins of the bug. Now this is how I have narrowed the problem. I am debuging with "raise Exception(request)" every time I want to know what's inside my request object. When I place this in my aboutUs method, the language cookie value changes every time I press the language button. But NOT when I am in the displayClothes method. There the language stays the same. Also I tried putting the exception line in the beginning of the @base method. It turns out the situation there is exactly the same. When I am in my About Us page and click on the button, the language in my request object changes, but when I press the button while in the catalog page it remains unchanged. That is all I could find, and I have no idea as to how Django distinguishes my pages and in what way. P.S. The JavaScript I think works perfectly, I have tested it in multiple ways. Thank you, I hope some of you will read this enormous post, and don't hesitate to ask for more code excerpts.

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  • Django: making raw SQL query, passing multiple/repeated params?

    - by AP257
    Hopefully this should be a fairly straightforward question, I just don't know enough about Python and Django to answer it. I've got a raw SQL query in Django that takes six different parameters, the first two of which (centreLat and centreLng) are each repeated: query = "SELECT units, (SQRT(((lat-%s)*(lat-%s)) + ((lng-%s)*(lng-%s)))) AS distance FROM places WHERE lat<%s AND lat>%s AND lon<%s AND lon>%s ORDER BY distance;" params = [centreLat,centreLng,swLat,neLat,swLng,neLng] places = Place.objects.raw(query, params) How do I structure the params object and the query string so they know which parameters to repeat and where?

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  • Sharepoint dynamic caml query problem?

    - by AB
    Hi, I want to dynamic caml query based on query string.Let me explain it with example my query sting can be anything ?cat=ABC&cat=ABD&cat=ABE... ?Cat=ABC ?Cat=ABC&cat=ABL so no. can be anything now the problem begins I want to query my sharepoint list based on this query string if (HttpContext.Current.Request.QueryString["cat"] != null) { string _cat = HttpContext.Current.Request.QueryString["cat"].ToString(); } so this way my string contains all the query string _cat=ABC,AD,....all. I want to query my sharepoint list based on these query string and with "AND" where title=ABC and title=AD .... if there is only one query string then only where title=ABC....so I want my query string should be dynamic.... Any idea how to acheive this??

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  • how to count all distinct records in many-to-many relations in django ORM?

    - by marduk-pl
    hi, i have two models: class Project(models.Model): categories = models.ManyToManyField(Category) class Category(models.Model): name = models.CharField() now, i make some queryset: query = Project.objects.filter(id__in=[1,2,3,4]) and i like to get list of all distinct categories in this queryset with count of projects with refering to these categories - exactly i would like to get that results: category1 - 10 projects category2 - 5 projects that is opposite to this query: query2 = query.annotate(Count('categories')) what return me: project1 - 2categories project2 - 7categories how can i make it in django ORM?

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  • Uploading file > 1 MB on Django admin gives 400 Bad Request response.

    - by ayaz
    I have a small Django (1.2.x) project deployed on Apache (2.x) via mod_wsgi (2.x). In the admin, if I upload a file < 1MB, I can get it through; however, for a file, say, 1.2MB in size, I get a 400 response from the server with "Error 400" in the body only. I am wondering why this is happening. As far as I can see, there is no LimitRequestBody set in Apache configuration. I have tried uploading with several browsers including: Firefox, Chrome, and Safari. In the log file for Apache, there is apparently no entry for requests that gave the 400 error response. This is strange. I should point out that the scenario where this is happening is thus: The project in question is deployed on two identical Apache servers (completely identical setup) that are behind a load balancer. On my development setup, of course, the problem does not surface. Any help with this will be very much appreciated.

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  • How to speed up request/response to django using apache or another solution?

    - by jbcurtin
    Hey all, I'm mainly a developer, but every now and again I jump into the sys-admin position. For the most part I've gotten away with deploying php and python apps using apache. I write today because I'm starting to research faster alternatives to apache, yet still have some of the core features I require like put and delete methods and the ability to connect to a socket via apache. ( This I have not tried, but might be a nice whistle if I ever employ comet on my apps. ) As you've probably guessed, I use javascript exclusively for all my websites utilizing deep linking for SEO support. The main areas that I'm looking to increase performance is the connection between the django apps and the web server to the client response. Every day I work my best to keep the smallest memory foot print as possible, however I am getting to the end of my rope when it comes to working with apache. In general, keep in mind that I'm just starting this research so I'm looking more for material to read then solutions at this moment. My main questions: Am I missing something about apache that makes it faster then everything else? What would be a good server environment to deploy just static files one? What are some of the leading open-source and paid alternatives?

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  • How should I implement reverse AJAX in a Django application?

    - by Carson Myers
    How should I implement reverse AJAX when building a chat application in Django? I've looked at Django-Orbited, and from my understanding, this puts a comet server in front of the HTTP server. This seems fine if I'm just running the Django development server, but how does this work when I start running the application from mod_wsgi? How does having the orbited server handling every request scale? Is this the correct approach? I've looked at another approach (long polling) that seems like it would work, although I'm not sure what all would be involved. Would the client request a page that would live in its own thread, so as not to block the rest of the application? Would it even block? Wouldn't the script requested by the client have to continuously poll for information? Which of the approaches is more proper? Which is more portable, scalable, sane, etc? Are there other good approaches to this (aside from the client polling for messages) that I have overlooked?

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  • Should we have a database independent SQL like query language in Django? [closed]

    - by Yugal Jindle
    Note : I know we have Django ORM already that keeps things database independent and converts to the database specific SQL queries. Once things starts getting complicated it is preferred to write raw SQL queries for better efficiency. When you write raw sql queries your code gets trapped with the database you are using. I also understand its important to use the full power of your database that can-not be achieved with the django orm alone. My Question : Until I use any database specific feature, why should one be trapped with the database. For instance : We have a query with multiple joins and we decided to write a raw sql query. Now, that makes my website postgres specific. Even when I have not used any postgres specific feature. I feel there should be some fake sql language which can translate to any database's sql query. Even Django's ORM can be built over it. So, that if you go out of ORM but not database specific - you can still remain database independent. I asked the same question to Jacob Kaplan Moss (In person) : He advised me to stay with the database that I like and endure its whole power, to which I agree. But my point was not that we should be database independent. My point is we should be database independent until we use a database specific feature. Please explain, why should be there a fake sql layer over the actual sql ?

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  • ByteFlow installation Error on Windows

    - by Patrick
    Hi Folks, When I try to install ByteFlow on my Windows development machine, I got the following MySQL error, and I don't know what to do, please give me some suggestion. Thank you so much!!! E:\byteflow-5b6d964917b5>manage.py syncdb !!! Read about DEBUG in settings_local.py and then remove me !!! !!! Read about DEBUG in settings_local.py and then remove me !!! J:\Program Files\Python26\lib\site-packages\MySQLdb\converters.py:37: DeprecationWarning: the sets module is deprecated from sets import BaseSet, Set Creating table auth_permission Creating table auth_group Creating table auth_user Creating table auth_message Creating table django_content_type Creating table django_session Creating table django_site Creating table django_admin_log Creating table django_flatpage Creating table actionrecord Creating table blog_post Traceback (most recent call last): File "E:\byteflow-5b6d964917b5\manage.py", line 11, in <module> execute_manager(settings) File "J:\Program Files\Python26\lib\site-packages\django\core\management\__init__.py", line 362, in execute_manager utility.execute() File "J:\Program Files\Python26\lib\site-packages\django\core\management\__init__.py", line 303, in execute self.fetch_command(subcommand).run_from_argv(self.argv) File "J:\Program Files\Python26\lib\site-packages\django\core\management\base.py", line 195, in run_from_argv self.execute(*args, **options.__dict__) File "J:\Program Files\Python26\lib\site-packages\django\core\management\base.py", line 222, in execute output = self.handle(*args, **options) File "J:\Program Files\Python26\lib\site-packages\django\core\management\base.py", line 351, in handle return self.handle_noargs(**options) File "J:\Program Files\Python26\lib\site-packages\django\core\management\commands\syncdb.py", line 78, in handle_noargs cursor.execute(statement) File "J:\Program Files\Python26\lib\site-packages\django\db\backends\util.py", line 19, in execute return self.cursor.execute(sql, params) File "J:\Program Files\Python26\lib\site-packages\django\db\backends\mysql\base.py", line 84, in execute return self.cursor.execute(query, args) File "J:\Program Files\Python26\lib\site-packages\MySQLdb\cursors.py", line 166, in execute self.errorhandler(self, exc, value) File "J:\Program Files\Python26\lib\site-packages\MySQLdb\connections.py", line 35, in defaulterrorhandler raise errorclass, errorvalue _mysql_exceptions.OperationalError: (1071, 'Specified key was too long; max key length is 767 bytes')

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  • django + south + python: strange behavior when using a text string received as a parameter in a func

    - by carlosescri
    Hello, this is my first question. I'm trying to execute a SQL query in django (south migration): from django.db import connection # ... class Migration(SchemaMigration): # ... def transform_id_to_pk(self, table): try: db.delete_primary_key(table) except: pass finally: cursor = connection.cursor() # This does not work cursor.execute('SELECT MAX("id") FROM "%s"', [table]) # I don't know if this works. try: minvalue = cursor.fetchone()[0] except: minvalue = 1 seq_name = table + '_id_seq' db.execute('CREATE SEQUENCE "%s" START WITH %s OWNED BY "%s"."id"', [seq_name, minvalue, table]) db.execute('ALTER TABLE "%s" ALTER COLUMN id SET DEFAULT nextval("%s")', [table, seq_name + '::regclass']) db.create_primary_key(table, ['id']) # ... I use this function like this: self.transform_id_to_pk('my_table_name') So it should: Find the biggest existent ID or 0 (it crashes) Create a sequence name Create the sequence Update the ID field to use sequence Update the ID as PK But it crashes and the error says: File "../apps/accounting/migrations/0003_setup_tables.py", line 45, in forwards self.delegation_table_setup(orm) File "../apps/accounting/migrations/0003_setup_tables.py", line 478, in delegation_table_setup self.transform_id_to_pk('accounting_delegation') File "../apps/accounting/migrations/0003_setup_tables.py", line 20, in transform_id_to_pk cursor.execute(u'SELECT MAX("id") FROM "%s"', [table.encode('utf-8')]) File "/Library/Python/2.6/site-packages/django/db/backends/util.py", line 19, in execute return self.cursor.execute(sql, params) psycopg2.ProgrammingError: relation "E'accounting_delegation'" does not exist LINE 1: SELECT MAX("id") FROM "E'accounting_delegation'" ^ I have shortened the file paths for convenience. What does that "E'accounting_delegation'" mean? How could I get rid of it? Thank you! Carlos.

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  • How can I change the Python that my Django project is using?

    - by Burak
    I have 2 versions installed in my server. I used virtualenv to install Python 2.7. I am using WSGI to deploy my project. WSGIPythonPath /home/ENV/lib/python2.7/site-packages WSGIScriptAlias / /var/www/html/my_project/wsgi.py My http.conf is like that. python -V gives Python 2.7.3 But in my projects Debug window, it says Django is using 2.6.8. Where am I wrong? UPDATE: Here is my wsgi file import os import sys sys.path.append('/var/www/html') os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myproject.settings") from django.core.wsgi import get_wsgi_application application = get_wsgi_application() Python Version: 2.6.8 Python Path: ['/home/ENV/lib/python2.7/site-packages/setuptools-0.6c11-py2.7.egg', '/home/ENV/lib/python2.7/site-packages/pip-1.1-py2.7.egg', '/home/ENV/lib/python2.7/site-packages/Django-1.4-py2.7.egg', '/home/ENV/lib/python2.7/site-packages', '/usr/lib/python2.6/site-packages/pip-1.1-py2.6.egg', '/usr/lib/python2.6/site-packages/django_transmeta-0.6.7-py2.6.egg', '/usr/lib/python2.6/site-packages/ipython-0.13-py2.6.egg', '/usr/lib/python2.6/site-packages/virtualenv-1.7.2-py2.6.egg', '/usr/lib64/python26.zip', '/usr/lib64/python2.6', '/usr/lib64/python2.6/plat-linux2', '/usr/lib64/python2.6/lib-tk', '/usr/lib64/python2.6/lib-old', '/usr/lib64/python2.6/lib-dynload', '/usr/lib64/python2.6/site-packages', '/usr/lib64/python2.6/site-packages/gtk-2.0', '/usr/lib/python2.6/site-packages', '/usr/lib/python2.6/site-packages/setuptools-0.6c11-py2.6.egg-info', '/var/www/html'] In my error_log of httpd: [Tue Jul 10 20:51:29 2012] [error] python_init: Python version mismatch, expected '2.6.7', found '2.6.8'. [Tue Jul 10 20:51:29 2012] [error] python_init: Python executable found '/usr/bin/python'. [Tue Jul 10 20:51:29 2012] [error] python_init: Python path being used '/usr/lib64/python26.zip:/usr/lib64/python2.6/:/usr/lib64/python2.6/plat-linux2:/usr/lib64/python2.6/lib-tk:/usr/lib64/python2.6/lib-old:/usr/lib64/python2.6/lib-dynload'.

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