T-SQL - sp_executesql语法

--方法1查询表改为动态

select * from sysobjects
exec('select ID,Name from sysobjects')
exec sp_executesql N'select ID,Name from sysobjects'--多了一个N为unicode

--方法2:字段名，表名，数据库名之类作为变量时,用动态SQL

declare @FName varchar(20)
set @FName='ID'
exec('select '+@FName+' from sysobjects where '+@FName+'=5' )


declare @s varchar(1000)
set @s=N'select '+@FName+' from sysobjects where '+@FName+'=5'
exec sp_executesql @s--会报错


declare @s nvarchar(1000)--改为nvarchar
set @s=N'select '+@FName+' from sysobjects where '+@FName+'=5'
exec sp_executesql @s--成功

--方法3:输入参数

declare @i int,@s nvarchar(1000)
set @i=5
exec('select ID,Name from sysobjects where ID='+@i)

set @s='select ID,Name from sysobjects where ID=@i'
exec sp_executesql @s,N'@i int',@i--此处输入参数要加上N

--方法4:输出参数

declare @i int,@s nvarchar(1000)
set @s='select @i=count(1) from sysobjects'

--用exec
exec('declare @i int '+@s+' select @i')--把整个语句用字符串加起来执行

--用sp_executesql
exec sp_executesql @s,N'@i int output',@i output--此处输出参数要加上N
select @i

--方法5:输入输出

--用sp_executesql
declare @i int,@con int,@s nvarchar(1000)
set @i=5
select @s='select @con=count(1) from sysobjects where ID>@i'
exec sp_executesql @s,N'@con int output,@i int',@con output ,@i
select @con

--用exec
declare @i int,@s nvarchar(1000)
set @i=5
select @s='declare @con int select @con=count(1) from sysobjects where ID>'+rtrim(@i)+' select @con'

--方法6:动态函数

declare @starttime datetime
declare @endtime datetime
set @starttime = '2009-02-20 00:00:05.680'
set @endtime = '2009-02-20 09:10:05.680'
declare @sql nvarchar(max)
set @sql= N'
select * from Conn_AdminIII_2009_02_10 where starttime between '''+ convert(nvarchar(200), @starttime, 120) +'''
and '''+ convert(nvarchar(200), @endtime, 120) +''' order by duration desc'
exec sp_executesql @sql