Question

我使用SQL Server 2005，我有这样的查询：

INSERT INTO [subject] ([sch_id],
                       [subj_from],
                       [subj_to],
)
SELECT
CASE
WHEN (SELECT @sched = [sch_id]
             FROM [schedule]
             WHERE [sch_name] = 'Searched Schedule Name') IS NULL THEN NULL
ELSE (SELECT @sched = [sch_id]
             FROM [schedule]
             WHERE [sch_name] = 'Searched Schedule Name')
END
AS 'sched_search_result',
   'Sample Value',
   'Sample Value'

这很好用。它在[subject]表中插入值，第一个值[sch_id]通过搜索的CASE语句从[schedule]表中获取。

我想避免代码冗余，所以我尝试将SELECT语句的结果存储在局部变量中，并使用ISNULL函数对其进行评估。看起来像这样：

DECLARE @sched INT
INSERT INTO [subject] ([sch_id],
                       [subj_from],
                       [subj_to],
)
SELECT
CASE ISNULL((SELECT @sched = [sch_id]
             FROM [schedule]
             WHERE [sch_name] = 'Searched Schedule Name'), 0)
WHEN 0 THEN NULL
ELSE @sched
END
AS 'sched_search_result',
   'Sample value',
   'Sample value'

但我的代码不起作用。 SQL Server 2005说错误来自我使用局部变量（@sched）的行。我的查询有什么问题？

Answer 1

我认为这会做你想要的。

INSERT INTO [subject] ([sch_id], [subj_from], [subj_to])
SELECT (
          SELECT [sch_id]
          FROM [schedule]
          WHERE [sch_name] = 'Search Schedule Name'
       ), 
      'from value',
      'to value'

Answer 2

这应该告诉你你需要什么：http://msdn.microsoft.com/en-us/library/aa259186(v=sql.80).aspx

SQL局部变量

2 个答案: