CASE 语句中的子查询

Question

So I'm trying to put a subquery within a CASE statement. The subquery itself is working fine, but if I put it in another code it can't process. What can I do best to solve?

CASE WHEN dbo.T1.TYPE = 0 
THEN dbo.Data.QTY * dbo.Data.SALESPRICE 
ELSE 
     CASE WHEN dbo.T1.TYPE = 1 
     THEN dbo.Data.QTY * 
          (
          SELECT        dbo.Data.ID, 
               CASE WHEN SUM(dbo.Data.QTY) = 0 
               THEN SUM(dbo.Data.SALESPRICE) 
               ELSE SUM(dbo.Data.SALESPRICE) / SUM(dbo.Data.QTY) 
               END AS REVph
          FROM  dbo.Data LEFT OUTER JOIN
               dbo.T1ON dbo.Data.ID = dbo.T1.ID
          WHERE         (dbo.T1.TYPE = 1)
          GROUP BY  dbo.Data.ID
         ) 
ELSE 0 
END 
END

Answer 1

You are using a subquery in a context where a single value is allowed. Such a subquery is called a scalar subquery .

However, the subquery is returning more than one column. That is not allowed. A scalar subquery can only return one column and at most one row.

Your question is rather unclear on what you want to accomplish, so I can only explain the problem that you are having.