构建SQL字符串的问题

Question

为什么这段代码不适合我？它给出了错误Must declare the scalar variable "@y".

DECLARE @y int
DECLARE @dbname VARCHAR(50)

SET @y = -1
SET @dbname = 'SomeDb.dbo.'

SET @sql = 'SELECT @y=1 from ' + @dbname + 'Respondent'

exec(@sql)

Answer 1

该exec函数创建一个新的执行范围.你的@y变量不存在.

请改用sp_executesql.请注意,您仍然需要做一些额外的工作来将变量传递到函数边界.

DECLARE @IntVariable int;
DECLARE @SQLString nvarchar(500);
DECLARE @ParmDefinition nvarchar(500);
DECLARE @max_title varchar(30);

SET @IntVariable = 197;
SET @SQLString = N'SELECT @max_titleOUT = max(Title) 
   FROM AdventureWorks.HumanResources.Employee
   WHERE ManagerID = @level';
SET @ParmDefinition = N'@level tinyint, @max_titleOUT varchar(30) OUTPUT';

EXECUTE sp_executesql @SQLString, @ParmDefinition, @level = @IntVariable, @max_titleOUT=@max_title OUTPUT;
SELECT @max_title;