動態語句的使用方法(exec/sp_executesql)
2013年09月17日
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- --动态语句语法
- 动态语句语法:
-
- --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'
- exec(@s)