declare @sql nvarchar(500)
set @sql=' select top 4 ID,InfoTitle,InfoClass,InfoAddTime From LocalInfo where InfoClass=''政策法规'''
exec(@sql)go
set @sql=' select top 4 ID,InfoTitle,InfoClass,InfoAddTime From LocalInfo where InfoClass=''政策法规'''
exec(@sql)go
InfoClass=''政策法规'' '
ALTER PROCEDURE TopInfoList
/*
(
@parameter1 datatype = default value,
@parameter2 datatype OUTPUT
)
*/
@TOPID nvarchar(50),
@InfoType nvarchar(50)ASdeclare @sql nvarchar(500)
set @sql=' select top '+@TOPID+' ID,InfoTitle,InfoClass,InfoAddTime From LocalInfo where InfoClass=''+@InfoType+'' '
exec(@sql)GO
set @sql=' select top 4 ID,InfoTitle,InfoClass,InfoAddTime From LocalInfo where InfoClass=' +'''' + '政策法规' +''''
exec(@sql)
动态sql语句基本语法
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