query tuning in sql server

Method 1:When the publisher filter condition is NULL, how do you write SQL?1 DECLARE @publishers VARCHAR (50);2 SELECT * FROM dbo. Book WHERE Publishers=isnull (@publishers, publishers)Method 2:DECLARE @cinv varchar (50)SELECT * from inventory where 1=1 and ([email protected] or @cinv is null)Method 3:DECLARE @name VARCHAR (+), @page INT =1SET @name = ' Zhang San 'DECLARE @sql VARCHAR (1000)SET @

To reduce the scope of the read operation, this article first looks at a simple select query and then introduces additional procedures related to performing the update operation. Finally, you will read that SQL Server uses the terminology and processes associated with the Restore tool when optimizing performance.relational and storage engines,

Tags: Scroll method prepare win section data body multiple ICAThe most obvious feature of SQL differs from other programming languages is the order in which the code is processed. In a large number programming language, code is processed in encoded order, but in the SQL language, the first processed clause is the FROM clause, although the SELECT statement first appears, but is almost always finally processe

T-SQL query advanced-understanding the lock introduction in SQL Server, each query will find the shortest path to achieve their goals. If the database only accepts one connection, only one query is executed at a time. Therefore, q

the CTESELECT *FROM cte_name递归执行的语义如下： 将 CTE 表达式拆分为定位点成员和递归成员。 Run an anchor member to create the first call or datum result set (T0). Run the recursive member, use Ti as the input, and ti+1 as the output. Repeat step 3 until the empty set is returned. Returns the result set. This is the result of the T0 to Tn execution of UNION all. Anchor member is definedThe location of the query is the data setT0, and thenRecursive m

into' Student 'VALUES('8','Lee 48','123','male',' +','Jingan, Shanghai city'); INSERT into' Student 'VALUES('9','Zhang 39','111','male',' +','Shiyan, Hubei province'); INSERT into' Student 'VALUES('Ten','Lee 40','123','male',' +','Jingan, Shanghai city'); I. Querying 5~10 data MySQL Paging query: SELECT * FROM student limit 5, 10; Oracle Paging query: SELECT * FROM (select *,rownum rn from student) wh

;--current session process ID SELECT @ @textSize; SELECT @ @version;--Current database version information 9. System Statistic function SELECT @ @CONNECTIONS;--Number of connections SELECT @ @PACK_RECEIVED; SELECT @ @CPU_BUSY; SELECT @ @PACK_SENT; SELECT @ @TIMETICKS; SELECT @ @IDLE; SELECT @ @TOTAL_ERRORS; SELECT @ @IO_BUSY; SELECT @ @TOTAL_READ;--Read disk count SELECT @ @PACKET_ERRORS;--Number of network packet errors that occurred SELECT @ @TOTAL_WRITE;--sqlserver the number of disk writes p

sqlpassion Performance Tuning Training Planindividual study translation, if there is falsehood, please do not hesitate to point out, thank you. Week 1:sql Server How to execute a query　　Before we go into the intricacies of SQL Server performance tuning, I'd like to start by

Label:Planning Cache (plan caches) If SQL Server has found a good way to execute a piece of code, it should be reused as a subsequent request because Generating execution plans is time-consuming and resource-intensive, There is a point in doing so. If the cached plan is not found, then command Parser generates a query tree on the T-

Label:SELECT B.deptname,A.badgenumber,A.userid,A.SSN,A.nameFROM dbo. USERINFO AINNER JOIN dbo. Departments B on a.defaultdeptid = B.deptidWHERE A.SSN is not NULLAnd b.deptid like '% ' Table ' USERINFO '. Scan count 1, logic read 278 times, physical read 0 times, pre-read 0 times.Table ' departments '. Scan count 1, logic read 4 times, physical read 0 times, pre-read 0 times. SQL Server Execution Time:CPU ti

the Name of the current Language. Select @ lock_timeout; -- returns the current lock timeout setting for the current session (MS) Select @ max_connections; -- returns the maximum number of user connections allowed by the SQL Server instance at the same time. Select @ MAX_PRECISION AS 'max Precision '; -- returns the Precision level used by the decimal and numeric data types. Select @ SERVERNAME; -- Name of

,-1, GETDATE ()),111)//111 is the style number, (100-114)Query first day of the month Date: Select DATEADD (mm, DATEDIFF (mm,0, GETDATE ()),0) asfirstday Query Last day of the month Date: Select DateAdd (MS,-3, DATEADD (mm, DATEDIFF (M,0, GETDATE ()) +1,0)) asLastday//change-The value of 3 changes accordinglyHow many days are there this month:SelectDatePart (Dd,dateadd (dd,-1, DateAdd (MM,1, Cast ((CAST (GE