数据库中：如何在存储过程中为一个变量，通过查询语句获赋值？

[qiuzhizhe]

在存储过程中定义一个变量通过查询语句却无法赋值，该怎么解决呢？
DECLARE @SchoolworkID INT
SET @SchoolworkID = 0----可以获取值
SET @SchoolworkID = (SELECT TOP 1 SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = @schoolworkPath))------但是这个语句就无法赋值，该怎么解决呢？


具体的存储过程如下：
CREATE PROCEDURE spUploadSchoolwork
@studentNO CHAR(6),
@schoolworkType CHAR(1),
@schoolworkPath VARCHAR(200),
---@teacherMarkedSign CHAR(1),
@schoolworkFileLength INT,
----uploadDay SMALLDATETIME DEFAULT GETDATE(),
@schoolworkFileType CHAR(5)
AS
DECLARE @SchoolworkID INT
SET @SchoolworkID = 0
SELECT @SchoolworkID = (SELECT TOP 1 SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = @schoolworkPath))------这里@SchoolworkID无法获取值，该怎么解决呢？
-----PRINT @SchoolworkID-------
IF (@SchoolworkID = 0)
BEGIN
INSERT INTO StudentSchoolwork
VALUES(@studentNO, @schoolworkType, @schoolworkPath, '0', @schoolworkFileLength, GETDATE(), @schoolworkFileType)
END
ELSE
BEGIN
UPDATE StudentSchoolwork
SET studentNO = @studentNO,
schoolworkFileLength = @schoolworkFileLength,
uploadDay = GETDATE()
WHERE SchoolworkID = @SchoolworkID
END
GO

[活靶子哥哥]

SET @SchoolworkID = (SELECT TOP 1 SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = @schoolworkPath))------但是这个语句就无法赋值，该怎么解决呢？


是有错误提示呢还是你运行过程中发现无法赋值

你在查询分析器内单独执行这部分看看到底有没有值

DECLARE @SchoolworkID INT
SET @SchoolworkID = (SELECT TOP 1 SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = '一个schoolworkpath的值'))
select @SchoolworkID

[qiuzhizhe]

无法赋值，不提示错误，而且这个存储过程已经建立成功了，楼上所说的方法在查询分析器中单独的这个语句是可以的，但是到了存储过程中同样的语句却却不能正确赋值

[milchcow]

SET @SchoolworkID = (SELECT TOP 1 SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = '一个schoolworkpath的值'))
select @SchoolworkID
改为：
SELECT TOP 1 @SchoolworkID =SchoolworkID FROM StudentSchoolwork WHERE(schoolworkPath = '一个schoolworkpath的值')
select @SchoolworkID

[liujiayu10]

declare @i int
select @i=cid from table where xx=1