query tuning in sql server

Read Catalogue Begin How SQL Server looks for records SQL Server Join method More specific execution procedures Index statistics: The choice of the query plan is based on Optimizing View Queries Recommended Reading-MSDN Articles For

Read SQL Server query planRead Catalogue Begin How SQL Server looks for records SQL Server Join method More specific execution procedures Index statistics: The

Label:Write in front: This is the first T-SQL query Advanced series article. But the T-SQL query step-up series is far from finished. This topic is advanced and I think it is because this topic requires some advanced knowledge as the basis. If there is any mistake in the article, please do not hesitate to correct me. T

Original address: http://www.cnblogs.com/lyhabc/p/3367274.htmlBefore reading this article, you can read the following article firstSQL Server's unique task scheduling algorithm "Sqlos"Task Scheduler for SQL Server Sqlos [go]Translated from:http://rusanu.com/2013/08/01/understanding-how-sql-server-executes-a-

Original: SQL Server 2012:SQL Server architecture--The life cycle of a query (part 3rd) (end)A simple update queryYou should now know the query life cycle of reading only the data, and next determine what happens when you need to

1. Use SET STATISTICS TIME ON -- First clear the cache Dbcc dropcleanbuffers; Dbcc freeproccache; -- Run Set statistics time on; SELECT orderid, custid, empid, shipperid, orderdate, filler FROM dbo. Orders WHERE orderdate> = '123' AND orderdate Set statistics time off; GO You will get a similar message: SQL Server Analysis and Compilation Time: CPU time = 15 ms, occupied time = 33 Ms.

Before: This is the first T-SQL query advanced seriesArticleBut the advanced series of T-SQL query is far from finished. I think this topic needs some advanced knowledge as the foundation. If there are errors in this article, please do not correct it. The content of this article requires the indexing knowledge as the b

You can use the SQL-Server Enterprise Manager to create an instance. Pay attention to RPC and RPC out. You can also use SQL statements to complete the definition, which involves three stored procedures. Sp_addmediaserver, sp_serveroption, and sp_addmediasrvlogin. the syntax of the three stored procedures is as follows: Sp_addmediaserverCreate a linked

'the value of the Key5' fromheadertable awhereA.headerid= 10000 SELECTA.*, t.a0001 as 'the value of the Key1', t.a0002 as 'the value of the Key2', t.a0003 as 'the value of the Key3', t.a0004 as 'the value of the Key4', t.a0005 as 'the value of the Key5' fromHeadertable AInner Join (SelectHeaderid, Detailkey, detailvalues fromdetailtable) T Pivot (MAX(detailvalues) forDetailkeyinch(a0001,a0002,a0003,a0004,a0005)) T onT.headerid=A.headeridwhereA.headerid= 10000 　　

key, and the primary key is not allowed to be null.ALTER TABLE dbo. Employees ADD constrant pk_employees PRIMARY KEY (empid);Create a PRIMARY KEY constraintUnique constraint: Enforces the uniqueness of the row, allowing the concept of alternate keys for the relational model to be implemented in its own database. Multiple unique constraints are allowed within the same table, no requirement to allow null for the field, but SQL

number for the T-SQLSelect @ procid;8. Configure FunctionsSet datefirst 7; -- set the first day of each week, indicating SundaySelect @ datefirst as 'Day of the Week', datepart (dw, getDate () AS 'Today is Week ';Select @ dbts; -- returns the unique timestamp of the current database.Set language 'Italian ';Select @ langId as 'language id'; -- returns the Language ID.Select @ language as 'language name'; -- returns the Name of the current Language.Select @ lock_timeout; -- returns the current lo

server| Speed | optimization MS SQL Server Query optimization method (1) There are many reasons for the slow query speed, common as follows: 1, no index or no index (this is the most common problem of query slow, is the defect of

the data is consistent, but nothing is perfect. The cost of the Begin Tran is that all the resources locked by the SQL statements cannot be released until the commit is committed before committing.It can be seen that if the BEGIN TRAN too many SQL statements, the performance of the database is poor. Before this large transaction commits, it is bound to block other statements, resulting in many blocks.The p

Analysis of SQL Server's focus on using indexes and query execution plans and SQL Execution plans Preface In the previous article "Analysis of the Impact of SQL Server focused indexes on non-clustered indexes", we talked about the impact of clustered indexes on non-clustered

files/Microsoft SQL Server/mssql10.mssqlserver/MSSQL/data/mydb. mdf d:/program files/Microsoft SQL Server/mssql10.mssqlserver/MSSQL/data/mydb_log.ldf (2 rows affected) */-- 3.2 mobile path use [Master] Go -- 3.2.1 disable all processes declare @ STR varchar (500); Set @ STR = ''; select @ STR = @ STR + 'Kill '+ rtrim

SQL Server Remote Login Server Management and query /* Data operations between databases on different servers */-- create a link to the server exec sp_add+server 'itsv', '', 'sqloledb ', 'remote

In the process of paging data using temporary tables, it is found that the query statement conditions are passed through the stored procedure parameters. The parameter conditions cannot be directly used after the SQL where statements are added. There is only one solution to this problem, it is to concatenate SQL statements and conditions into an

In programming languages with large numbers, the code is processed in the encoding order, but in SQL, the first clause to be processed is the FROM clause. Although the first SELECT statement appears, but it is almost always processed.Each step generates a virtual table, which is used as the input for the next step. These virtual tables are unavailable to callers (client applications or external queries. Only the table generated in the last step will b

it is to increase I/O.2. Vertical and horizontal partition table, reduce the size of the table (Sp_spaceuse)3. Upgrading hardware4, according to the query criteria, index, optimize the index, optimize access mode, limit the data volume of the result set. Note that the fill factor is appropriate (preferably using the default value of 0). The index should be as small as possible, using a Lie Jian index with a small number of bytes (refer to the creatio

row within the result set partition. The rank of a row is a number of rows before the line involved. --like here I sort by price, take out the most expensive items in each category from top to bottom SELECT * from ( SELECTI.price,i.commodityname,c.classname,rank () Over(Partition byC.classidOrder byI.priceDESC) Rank2 fromCommodityinfo iINNER JOINCommodityclass C onI.commodityclass=C.classid) RWHERERank22; Under SQL