我想在sql语句里写个语句,它自己写个sql语句再执行
1.写sql语句
select count(*) as times, areaname as 地区 from AreaTable where @therCondition
2.给此语句的@therConditon 赋值
我设置 @therCondition= " areaID=12 "
3.sql语句自己组合
(然后他就变成了)
select count(*) as times, areaname as 地区 from AreaTable where areaID=12
4.再执行
请问怎么做
------解决方案--------------------写个存储过程,将@therCondition传进去
create proc test1
@therCondition nvarchar(500)
as
exec( 'select count(*) as times, areaname as 地区 from AreaTable where ' + @therCondition )
------解决方案--------------------用存储过程
Create Procedure GetID @therCondition int
as
select count(*) as times, areaname as 地区
from AreaTable
where areaID=@therCondition
执行时运行
execute GetID 12
------解决方案--------------------hb_gx(高升) 兄弟正解
------解决方案--------------------用动态SQL语句。
exec( 'select count(*) as times, areaname as 地区 from AreaTable where ' + @therCondition )
------解决方案-------------------- 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,
@sql nvarchar(4000)
set @sql= 'select count(*) from tableName '
exec(@sql)
--如何将exec执行结果放入变量中?
declare @num int, @sql nvarchar(4000)
set @sql= 'select @a=count(*) from tableName '
exec sp_executesql @sql,N '@a int output ',@num output
select @num