An acronym for "Structured Query Language" (it's not the name of a specific DBMS product), SQL can be used in relational database management systems (RDBMS) to query, update, delete, and insert data as well as modify the structure of the database. It can also be used to manage schemas and data ...

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Methods of speeding up a huge DELETE FROM <table> with no clauses

Using SQL Server 2005. I am performing a huge DELETE FROM with no where clauses. It's basically equivalent to a TRUNCATE TABLE statement - except I'm not allowed to use TRUNCATE. The problem is ...
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How to select the first row of each group?

I have a table like this: ID | Val | Kind ---------------------- 1 | 1337 | 2 2 | 1337 | 1 3 | 3 | 4 4 | 3 | 4 I want to make a SELECT that will return just the ...
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LIKE uses index, CHARINDEX does not?

This question is related to my old question. The below query was taking 10 to 15 seconds to execute: SELECT [customer].[Customer name],[customer].[Sl_No],[customer].[Id] FROM [company].dbo.[customer] ...
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How do you clear out all old query plans from within Microsoft SQL Server?

We have an off the shelf application that uses a Microsoft SQL database. Within this application we pick and choose various selection criteria for each report. This application then runs these ...
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How do I query this 20 million record view faster?

For a search functionality I am using a view that has the records from all the tables within which I need to search for. The view has almost 20 million records. Searches against this view are taking ...
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Used Memory not freed up after a SQL BULK Insert / BCP Export

I have created a very basic SQL table as following CREATE TABLE [dbo].[TickData]( [Date] [varchar](12) NULL, [Time] [varchar](12) NOT NULL, [Symbol] [varchar](12) NOT NULL, [Side] [varchar](2) ...
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PostgreSQL procedural languages - differences between PL/pgSQL and SQL

Can anybody please summarize the differences between: http://www.postgresql.org/docs/9.1/static/xfunc-sql.html and http://www.postgresql.org/docs/9.1/static/plpgsql.html ? Main points: ...
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Postgres query plan of a UDF invocation written in pgpsql

It's possible when using the pgadmin or plsql to get a hold of a query plan for a sql statement executed via a UDF (using EXPLAIN). So, how do I get a hold of the query plan for a particular ...
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Optimization: Moving variable declarations to the top of your procedure

While working on optimizing some stored procedures, I sat down with the DBA and went through some sprocs with high blocking and/or high read/write activity. One thing the DBA mentioned was I should ...
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Notification on long-running query or deadlock in SQL Server 2008 R2?

I'd like to know if there is a way to send a notification on deadlock? If so what queries would be required. I understand that SQL Server takes care of deadlocks, I simply would like information on ...
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How many Sproc Parameters is too many?

I've just started writing a Stored Procedure in SQL Server 2008 and have 30+ parameters. I've never written one with more than ~10 parameters, and that got me thinking... At what point are there too ...
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Query Performance Tuning

When you finish writing a query/stored proc/function, what's the most informative way to quickly get some performance parameters? Do you run the query and view the actual execution plan? If so, what ...
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Varchar(Max) field cutting off data after 8000 characters SQL Server 2008

I have a field to store some data, the field is declared as varchar(Max). To my understanding this should be storing 2^31 - 1 characters but when I enter some content over 8000 chars it cuts the rest ...
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1answer
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Order by column should have index or not?

I have added indexes to table which are used for searching result. I am showing results by ASC or DESC order. So that column should have index or not? I have 2 more indexes on that table. How ...
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Reasons for occasionally slow queries?

We are running MySQL 5.1 on Windows Server 2008 R2. We have been doing some diagnostics on our database of late and have found some disturbing artifacts which we can't explain. We added some code to ...
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Why is an aggregate query significantly faster with a GROUP BY clause than without one?

I'm just curious why an aggregate query runs so much faster with a GROUP BY clause than without one. For example, this query takes almost 10 seconds to run SELECT MIN(CreatedDate) FROM MyTable WHERE ...
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Updating 700 million rows to same value

I've got a data warehouse (oracle) where I need to set a column to the same value for all 700 million rows. I don't have admin access, or access to an admin, so this needs to be accomplished with ...
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Slow Performance Inserting Few Rows Into Huge Table

We have a process that takes data from stores and updates a company-wide inventory table. This table has rows for every store by date and by item. At customers with many stores, this table can get ...
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Efficiently Filter Large Set With Disjunctions

Let's say I have a single table CREATE TABLE Ticket ( TicketId int NOT NULL, InsertDateTime datetime NOT NULL, SiteId int NOT NULL, StatusId tinyint NOT NULL, AssignedId int NULL, ...
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Treating certain Arabic characters as identical

In Arabic we have characters like ا (alef) and أ (alef with hamza). Users write them interchangeably and we want to search them interchangeably. SQL Server treats them as separate characters. How ...
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Group By hour over large dataset

Using MS SQL 2008 I am selecting an averaged field from 2.5 million records. Each record represents one second. MyField is an hourly average of those 1 second records. Of course the server CPU hits ...
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Fastest way to change a 600GB table indexed key datatype from INT to BIGINT

I need to change a datatype from INT to BIGINT in a 600GB MySQL table. The column has a unique index. I might be good with unsigned INT, but I assume changing to that or BIGINT will be pretty much ...
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Fast SQL query with * but extremely slow with specific columns? [closed]

We have a query that we're running on SQL Server 2008 in the Management Studio. I can't give the exact query details, but let's say it's equivalent to this: SELECT * FROM MyView a (nolock) INNER ...
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Why is the SELECT clause listed first? [closed]

I'm not sure if this question is on-topic - if not, feel free to close. Also, if it'd be a better question for another StackExchange site, I can ask it elsewhere. I was wondering why SQL places the ...
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SQLITE: A problem of tags and products

I'm searching for a way to create a query to do the following: Let's consider 3 tables: products: List of products tags: list of tags tag_ties: table used to associate a tag to a product Let's ...
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Backing up SQL DB more frequently

I currently have a scheduled task that fires off each night at 2 AM that calls SQLCMD.exe and passes it a .sql script to run for the backup (shown below). We're a pretty small company with growing ...
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Can I see Historical Queries run on a SQL Server database?

Someone was running a query on our SQL Server database remotely and their system crashed. They have no backup of that query and want to see what was run on the server. Is it possible to find this ...
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Query Running Differently on SQL 2005 vs SQL 2008R2

At my office, we have a query that is pretty ugly, but runs pretty well in production and in the development environment (20sec, and 4sec respectively). However in our testing environment it takes ...
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How to differentiate between SQL and PL/SQL?

I know the question might sound too stupid, but I never understood this part. SQL*Plus works with both SQL and PL/SQL. How do I know whether some code is SQL or PL/SQL? If my code has a for ...
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Oracle sort varchar2 column with special characters last

How can I sort in Oracle a Varchar2 or NVarchar2 column to be in my own custom defined order. Or are any existing options available that will put letters first, then numbers, then all special ...
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Does MySQL cache queries?

I'm interfacing a MySQL database with PHP Data Objects (PDO) and executing an extensive SQL query. Normally, it takes about 1500 ms; I still need to optimize it. When I run the PHP script twice ...
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Storing date as integer (numeric), what are the advantages

Question 1 I am working with a system where date is stored as integer (actual numeric(8,0)) and I have noticed that other systems also store date as int such as cisco in this thread. Example ...
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How do I show the binlog_format on a MySQL server?

How do I show the binlog_format on a MySQL server? And if I dont like it how do I set it to XX permanently? Where XX is STATEMENT, ROW or MIXED.
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How to force drop database in SQL Server 2008

I'm trying to force drop a database, but after dropping the database, when I try to recreate the database, I'm getting the error cannot create file C:\Program Files.....[databasename].mdf because ...
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Alter table on live production databases

How do most "popular" (MySQL, Postgres...) database system handle altering tables on live production databases (like adding, deleting or changing the type of colums)? I know the correct way is to ...
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Non-Clustered Indexes - keys and nonkeys

I just want to make sure I'm on the right track with these concepts, so any feedback would be greatly appreciated. Here's my theory from the query I've just optimised, through a process of trial and ...
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overstating field size in database design

I have some fields for my tables that are strings and at the moment, most of the field size have pretty high character limits. For instance, 100 char for the street name. Is there a penalty for using ...
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What are the alternatives for an ORDER BY clause in a View?

This question just had to be in this site :) ORDER BY is forbidden to use in a view, as I understood because of the possibility for multiple order by's when using this view. I know that there are ...
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When a previously-fast SQL query starts running slow, where do I look to find the source of the issue?

Background I have a query running against SQL Server 2008 R2 that joins and/or left-joins about 12 different "tables". The database is fairly large with many tables over 50 million rows and about 300 ...
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Oracle: How do I query a Hierarchical table?

Background This is for the construction of some views we'll be using for reporting. I have an table of locations, the key fields being "location" and "parent". The structure that these two fields ...
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What is the best way to find out how many records do not have a proper phone number in SQL Server?

I have a field that people historically could use to freely supply a value. I need to identify the records which do not have an appropriate value so I can clean them. I've been looking around in SSIS ...
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function hangs with null case operation

I created a function that accepts a start and end date, with the end date being optional. I then wrote a CASE in the filter to use the start date if no end date is passed. CASE WHEN @dateEnd IS NULL ...
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Where can I find the SQL standard document?

Where can I find a legal copy of the ISO SQL 2008 standard?
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How to boost performance of virgin queries in MS SQL Server?

I have ASP.NET web site that does it's own independent caching of data and data does not change for long periods of time, so it does not need to query SQL Server second time with same query. I need to ...
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How can I optimize this MySQL query further?

I have a query that is taking a particularly long time to run (15+ seconds) and it is only getting worse with time as my dataset grows. I have optimized this in the past, and have added indices, ...
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Is there a way to programmatically script all objects associated with a given table?

I know that in SQL management studio I can right click a table/trigger/key and script object as.... Is there a way to do this programmatically, given an object's name? If so, is there a way to find ...
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1answer
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Deadlock when update different rows with non-clustered index

I'm solving a deadlocking issue while I noticed the lock behavior is different when I use clustered and non-clustered index on the id field. The deadlock issue seems to be solved if clusted index or ...
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How to delete a procedure which name is ambigous?

I am using informix... I dont know how i did it, but there are two procedures with the same name in my database. When i try to remove them with a DROP PROCEDURE myProc; then i get a error message ...
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SQL Server query slow when paginated

I am seeing some strange behaviour with the following T-SQL query in SQL Server 2012: select Id FROM dbo.Person WHERE CONTAINS(Name, '"John" AND "Smith"') order by Name Executing this query alone ...
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When should indexes be dropped and recreated?

We are constructing a data warehouse that initially will be 1 TB and will grow around 20gigs every month. For certain tables we are doing daily ETL processes and others we are doing weekly/monthly. ...