临时表 本地临时表 适合开销昂贵 结果集是个非常小的集合 -- Local Temporary Tables IF OBJECT_ID('tempdb.dbo.#MyOrderTotalsByYear') IS NOT NULL DROP TABLE dbo.#MyOrderTotalsByYear; GO CREATE TABLE #MyOrderTotalsByYear ( orderyear INT NOT NULL PRIMARY KEY, qty INT NOT NULL ); I…
1.Split SQL Server 2008 新语法: DECLARE @str VARCHAR(MAX) SET @str = REPLACE(@teeIDs, ',', '''),(''') SET @str = 'SELECT * FROM (VALUES(''' + @str + ''')) AS V(A)' EXEC (@str) 据说这个SQL语法是SQL Server 2008的. SELECT * FROM (VALUES(1),(2),(3)) AS V(A) 配合个临…
在SQL 2012基础教程中列出子句是按照以下顺序进行逻辑处理. FROM WHERE GROUP BY HAVING SELECT ORDER BY FROM TableName WHERE UserCode = @UserCode) BEGIN UPDATE TableName SET NotPushBeginTime = @NotPushBeginTime, NotPushEndTime = @NotPushEndTime WHERE UserCode = @UserCode END EL…
测试数据脚本 CREATE TABLE Atable ( S# INT, Sname ), Sage INT, Sfrom ) ) insert into Atable ,N,N'A' union all ,N, N'A' union all ,N,N'A' union all ,N,N'A' CREATE TABLE Btable ( S# INT, Sname ), Sage INT, Sfrom ) ) insert into Btable ,N,N'B' union all ,N,N'B…
找到消耗内存最多的SQL SELECT mg.granted_memory_kb, mg.session_id, t.text, qp.query_plan FROM sys.dm_exec_query_memory_grants AS mg CROSS APPLY sys.dm_exec_sql_text(mg.sql_handle) AS t CROSS APPLY sys.dm_exec_query_plan(mg.plan_handle) AS qp ) 是不使用Not In,而使用No…
create unique index 和create index 的区别? CREATE UNIQUE INDEX ProviderInfo_Id_uindex ON dbo.ProviderInfo(Id) create unique index 是创建唯一索引,但前提是列上的数据不能有重复值. create index不是唯一索引,只是在创建索引. SQL聚集索引和非聚集索引的区别 根据索引的顺序与数据表的物理顺序是否相同,可以把索引分成两种类型: 聚簇索引,数据表的物理顺序与索引顺序相…
概述 ROW_NUMBER() OVER(PARTITION BY CustId ORDER BY ID DESC) https://www.jb51.net/article/75533.htm 开窗函数 SELECT empid, ordermonth, val, SUM(val) OVER(PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS runval FRO…
示例数据库 点我下载 一条完整的sql语句 select top | distinct 字段, 表达式, 函数, ... from 表表达式 where 筛选条件 group by 分组条件 having 筛选条件 order by 排序依据; SQL的执行顺序: 运算符的优先级 SELECT语句的元素 SELECT empid, YEAR(orderdate) AS orderyear, COUNT(*) AS numorders FROM Sales.Orders GROUP BY empi…
use electric go --变量 --局部变量的声明格式 --declare @局部变量名 数据类型 --局部变量赋值 declare @littlepage int )) ) select @little=warehouse from Stock print @little -- --存储过程 -- --if else 语法 --在电力抢修工程数据库中,如果stock表中存在库存量低于1的物资,就显示文本:the amount is not enough:否则显示所有物资信息. ) p…
变量 --------------------------------------------------------------------- -- Variables --------------------------------------------------------------------- -- Declare a variable and initialize it with a value DECLARE @i AS INT; ; GO -- Declare and in…
我创建了INNER JOIN 9桌,反正需要很长的(超过五分钟).所以,我的民歌改变INNER JOIN来LEFT JOIN LEFT JOIN的性能较好,在首次尽管我所知道的.之后我变了,查询的速度显著提高. 我想知道为什么LEFT JOIN的速度比INNER JOIN? 我的样子如下:SELECT * FROM A INNER JOIN B ON ... INNER JOIN C ON ... INNER JOIN D因此没有 更新: 这是我的简单架构的. FROM sidisaleshdr…
