SQL Select 在子查询中

Question

您好我的查询如下，其中包含一个子查询：

ALTER PROCEDURE [dbo].[POBalance] @PONumber NVARCHAR(50) 
AS
BEGIN
    SELECT CASE 
            WHEN X.STATUS = 'False'
                THEN (  SELECT A.Description
                            ,C.qty AS POqty
                            ,B.Qty AS PDQty
                            ,CASE 
                                WHEN A.partialflag = 'false'
                                    THEN '0'
                                ELSE A.qty
                                END AS Balance
                            ,A.Unit
                            ,A.Unitprice
                            ,A.Partialflag
                        FROM tblPOdetails AS A
                        INNER JOIN tblPDdetails AS B ON A.id = B.id
                        INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                        WHERE A.PONo = @PONumber
                        )
            ELSE (  SELECT A.Description
                        ,C.qty AS POqty
                        ,B.Qty AS PDQty
                        ,C.qty AS Balance
                        ,A.Unit
                        ,A.Unitprice
                        ,A.Partialflag
                    FROM tblPOdetails AS A
                    INNER JOIN tblPDdetails AS B ON A.id = B.id
                    INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                    WHERE A.PONo = @PONumber)
            END
    FROM tblPOHeader AS X
    WHERE x.PONo = @PONumber
END

我得到的错误是：

当子查询不存在时，select列表中只能指定一个表达式与 EXISTS 一起引入。

我的查询有什么问题..看来我的子查询没问题。

提前致谢

Answer 1

您不能 select 多个字段为一个 expression.Your 别名使它更多 visible.You select 多个值并且只给出一个别名！！请参考这个

Only One Expression in case

And this one too

Another one here

Answer 2

你不能select table 以防万一。你可以这样做（我没有测试它）：

    SELECT A.Description
                                ,C.qty AS POqty
                                ,B.Qty AS PDQty
                                ,CASE 
                                    WHEN A.partialflag = 'false'
                                        THEN '0'
                                    ELSE A.qty
                                    END AS Balance
                                ,A.Unit
                                ,A.Unitprice
                                ,A.Partialflag
                            FROM tblPOdetails AS A
                            INNER JOIN tblPDdetails AS B ON A.id = B.id
                            INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                            INNER JOIN tblPOHeader X ON x.PONo = A.PONo
                            WHERE A.PONo = @PONumber and X.STATUS = 'False'

    UNION ALL

    SELECT A.Description
                            ,C.qty AS POqty
                            ,B.Qty AS PDQty
                            ,C.qty AS Balance
                            ,A.Unit
                            ,A.Unitprice
                            ,A.Partialflag
                            FROM tblPOdetails AS A
                            INNER JOIN tblPDdetails AS B ON A.id = B.id
                            INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                            INNER JOIN tblPOHeader X ON x.PONo = A.PONo
                            WHERE A.PONo = @PONumber and X.STATUS <> 'False'

但我认为 tah X.STATUS 有点 - 如果是的话，你应该这样做：

    SELECT A.Description
                                ,C.qty AS POqty
                                ,B.Qty AS PDQty
                                ,CASE 
                                    WHEN A.partialflag = 'false'
                                        THEN '0'
                                    ELSE A.qty
                                    END AS Balance
                                ,A.Unit
                                ,A.Unitprice
                                ,A.Partialflag
                            FROM tblPOdetails AS A
                            INNER JOIN tblPDdetails AS B ON A.id = B.id
                            INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                            INNER JOIN tblPOHeader X ON x.PONo = A.PONo
                            WHERE A.PONo = @PONumber and X.STATUS = 0

    UNION ALL

    SELECT A.Description
                            ,C.qty AS POqty
                            ,B.Qty AS PDQty
                            ,C.qty AS Balance
                            ,A.Unit
                            ,A.Unitprice
                            ,A.Partialflag
                            FROM tblPOdetails AS A
                            INNER JOIN tblPDdetails AS B ON A.id = B.id
                            INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                            INNER JOIN tblPOHeader X ON x.PONo = A.PONo
                            WHERE A.PONo = @PONumber and X.STATUS <> 0

Answer 3

你真的在找这个吗？

ALTER PROCEDURE [dbo].[POBalance] @PONumber NVARCHAR(50)
AS
BEGIN
    DECLARE @Status NVARCHAR(MAX)

    SELECT @Status = X.STATUS
    FROM tblPOHeader AS X WHEREx.PONo = @PONumber

    IF @Status = 'False'
    BEGIN
        SELECT A.Description
            ,C.qty AS POqty
            ,B.Qty AS PDQty
            ,CASE 
                WHEN A.partialflag = 'false'
                    THEN '0'
                ELSE A.qty
                END AS Balance
            ,A.Unit
            ,A.Unitprice
            ,A.Partialflag
        FROM tblPOdetails AS A
        INNER JOIN tblPDdetails AS B ON A.id = B.id
        INNER JOIN tblpodetailshistory AS C ON A.id = C.id
        WHERE A.PONo = @PONumber
    END
    ELSE
    BEGIN
        SELECT A.Description
            ,C.qty AS POqty
            ,B.Qty AS PDQty
            ,C.qty AS Balance
            ,A.Unit
            ,A.Unitprice
            ,A.Partialflag
        FROM tblPOdetails AS A
        INNER JOIN tblPDdetails AS B ON A.id = B.id
        INNER JOIN tblpodetailshistory AS C ON A.id = C.id
        WHERE A.PONo = @PONumber
    END
END

此代码将存储并检查 @Status 的值，并根据该值是否为 False 然后它将 return 查询之一的结果集.

Answer 4

何时

select * from tblPOHeader where PONo = @PONumber

returns 只有一行你可以做类似的事情

    declare @STATUS nvarchar(200) = ( select STATUS from tblPOHeader where PONo = @PONumber)
    if @STATUS = 'False'
    SELECT A.Description
                            ,C.qty AS POqty
                            ,B.Qty AS PDQty
                            ,CASE 
                                WHEN A.partialflag = 'false'
                                    THEN '0'
                                ELSE A.qty
                                END AS Balance
                            ,A.Unit
                            ,A.Unitprice
                            ,A.Partialflag
                        FROM tblPOdetails AS A
                        INNER JOIN tblPDdetails AS B ON A.id = B.id
                        INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                        WHERE A.PONo = @PONumber 

    ELSE
        SELECT A.Description
                        ,C.qty AS POqty
                        ,B.Qty AS PDQty
                        ,C.qty AS Balance
                        ,A.Unit
                        ,A.Unitprice
                        ,A.Partialflag
                        FROM tblPOdetails AS A
                        INNER JOIN tblPDdetails AS B ON A.id = B.id
                        INNER JOIN tblpodetailshistory AS C ON A.id = C.id
                        WHERE A.PONo = @PONumber

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