set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
gocreate PROCEDURE [dbo].[test]
AS
declare @sqlstr1 nvarchar(100)
declare @sqlstr2 nvarchar(100)set @sqlstr1 ='test'+CONVERT(char(4),getdate()-1,12)
set @sqlstr2 ='testtable'+CONVERT(char(6),getdate()-1,12)BEGIN if not exists('select name from '+@sqlstr1+'.dbo.sysobjects where name='+@sqlstr2)
drop table test.dbo.testtableendGO
set QUOTED_IDENTIFIER ON
gocreate PROCEDURE [dbo].[test]
AS
declare @sqlstr1 nvarchar(100)
declare @sqlstr2 nvarchar(100)set @sqlstr1 ='test'+CONVERT(char(4),getdate()-1,12)
set @sqlstr2 ='testtable'+CONVERT(char(6),getdate()-1,12)BEGIN if not exists('select name from '+@sqlstr1+'.dbo.sysobjects where name='+@sqlstr2)
drop table test.dbo.testtableendGO
1 :普通SQL语句可以用Exec执行 eg: Select * from tableName
Exec('select * from tableName')
Exec sp_executesql N'select * from tableName' -- 请注意字符串前一定要加N 2:字段名,表名,数据库名之类作为变量时,必须用动态SQL eg:
declare @fname varchar(20)
set @fname = 'FiledName'
Select @fname from tableName -- 错误,不会提示错误,但结果为固定值FiledName,并非所要。
Exec('select ' + @fname + ' from tableName') -- 请注意 加号前后的 单引号的边上加空格 当然将字符串改成变量的形式也可
declare @fname varchar(20)
set @fname = 'FiledName' --设置字段名 declare @s varchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句会报错 declare @s Nvarchar(1000) -- 注意此处改为nvarchar(1000)
set @s = 'select ' + @fname + ' from tableName'
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确 3. 输出参数
declare @num int,
@sqls nvarchar(4000)
set @sqls='select count(*) from tableName'
exec(@sqls)
--如何将exec执行结果放入变量中? declare @num int,
@sqls nvarchar(4000)
set @sqls='select @a=count(*) from tableName '
exec sp_executesql @sqls,N'@a int output',@num output
select @num
set QUOTED_IDENTIFIER ON
go create PROCEDURE [dbo].[test]
AS
declare @sqlstr1 nvarchar(100)
declare @sqlstr2 nvarchar(100) set @sqlstr1 ='test'+CONVERT(char(4),getdate()-1,12)+'.dbo.sysobjects'
set @sqlstr2 ='testtable'+CONVERT(char(6),getdate()-1,12) BEGIN if not exists(select name from @sqlstr1 where name=@sqlstr2)
drop table test.dbo.testtable end GO改成这样后提示 必须声明表变量“@sqlstr1“,但是库名我想用变量带入
set QUOTED_IDENTIFIER ON
go create PROCEDURE [dbo].[test]
AS
declare @sqlstr1 nvarchar(100)
declare @sqlstr2 nvarchar(100) set @sqlstr1 ='test'+CONVERT(char(4),getdate()-1,12)+'.dbo.sysobjects'
set @sqlstr2 ='testtable'+CONVERT(char(6),getdate()-1,12) BEGIN
exec('select name from '+@sqlstr1+'.dbo.sysobjects where name='+@sqlstr2)
if @@rowcount=0
drop table test.dbo.testtable end GO