1:
普通SQL语句可以用Exec执行
eg: Select * from tableName
Exec(@#select * from tableName@#)
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 = @#[name]@#
Select @fname from sysobjects -- 错误
Exec(@#select @# + @fname + @# from sysobjects@#) -- 请注意 加号前后的 单引号的边上要加空格
exec sp_executesql N@# select @# + @fname + @# from sysobjects@#
当然将字符串改成变量的形式也可
declare @s varchar(1000)
set @s = @#select @# + @fname + @# from sysobjects@#
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 sysobjects@#
Exec(@s) -- 成功
exec sp_executesql @s -- 此句正确，
3: 输出参数
eg:
declare @num,
@sqls
set @sqls=@#select count(*) from @# + @servername + @#.a.dbo.b@#
exec(@sqls)
我如何能将exec执行的结果存入变量@num中
declare @num int,
@sqls nvarchar(4000)
set @sqls=@#select @a=count(*) from @#+@servername+@#.a.dbo.b@#
exec sp_executesql @sqls,N@#@a int output@#,@num output
select @num
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