Question

这是我的SQL查询。我有一个表A，但当我尝试将此表用于HAVING（A.CATEGORY）时显示错误ORA-00979: not a GROUP BY expression。另一方面，如果我在同一个地方复制表A中的所有代码，它就可以工作。如何让这个查询在第一路上正常工作？感谢

第一（不正确）：

SELECT
    DEMO_PRODUCT_INFO.PRODUCT_NAME
FROM
    DEMO_PRODUCT_INFO,
    (SELECT
        DEMO_PRODUCT_INFO.CATEGORY
     FROM
        DEMO_PRODUCT_INFO
    HAVING
        MAX(DEMO_PRODUCT_INFO.LIST_PRICE) 
        = (SELECT MAX(MAX(DEMO_PRODUCT_INFO.LIST_PRICE)) 
             FROM DEMO_PRODUCT_INFO 
            GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
    GROUP BY
        DEMO_PRODUCT_INFO.CATEGORY) A
WHERE
    DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY
HAVING
    MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
    = (SELECT MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
        FROM DEMO_PRODUCT_INFO 
       WHERE DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY 
       GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
GROUP BY
    DEMO_PRODUCT_INFO.PRODUCT_NAME

SECOND（CORRECT）：

SELECT
    DEMO_PRODUCT_INFO.PRODUCT_NAME
FROM
    DEMO_PRODUCT_INFO,
    (SELECT
        DEMO_PRODUCT_INFO.CATEGORY
     FROM
        DEMO_PRODUCT_INFO
    HAVING
        MAX(DEMO_PRODUCT_INFO.LIST_PRICE) 
        = (SELECT MAX(MAX(DEMO_PRODUCT_INFO.LIST_PRICE)) 
             FROM DEMO_PRODUCT_INFO 
            GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
    GROUP BY
        DEMO_PRODUCT_INFO.CATEGORY) A
WHERE
    DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY
HAVING
    MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
    = (SELECT MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
        FROM DEMO_PRODUCT_INFO 
       WHERE DEMO_PRODUCT_INFO.CATEGORY 
             = (SELECT DEMO_PRODUCT_INFO.CATEGORY
                  FROM DEMO_PRODUCT_INFO
                HAVING MAX(DEMO_PRODUCT_INFO.LIST_PRICE) 
                       = (SELECT MAX(MAX(DEMO_PRODUCT_INFO.LIST_PRICE)) 
                            FROM DEMO_PRODUCT_INFO 
                           GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
                 GROUP BY DEMO_PRODUCT_INFO.CATEGORY) 
       GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
GROUP BY
    DEMO_PRODUCT_INFO.PRODUCT_NAME

Answer 1

GROUP BY子句在HAVING子句之前。这是正确的顺序：

SELECT ...
FROM ...
WHERE ...
GROUP BY ...
HAVING ...

Answer 2

我不是你想要做的100％，但错误是因为你的脚本的这一部分：

HAVING
    MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
    = (SELECT MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
        FROM DEMO_PRODUCT_INFO 
       WHERE DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY 
       GROUP BY DEMO_PRODUCT_INFO.CATEGORY)

select min(ilst_price)...group by category将生成list_prices列表。因此having子句有效地说“只有最小list_prices 等于最小list_prices列表的行，按类别分组”。当然，这是不合逻辑的。

我假设你想要该类别的最低list_price？您需要删除group by。此外，list {price周围的min()需要位于内部选择的外部。这是一个完整的工作版本：

SELECT
    DEMO_PRODUCT_INFO.PRODUCT_NAME
FROM
    DEMO_PRODUCT_INFO,
    (SELECT
        DEMO_PRODUCT_INFO.CATEGORY
     FROM
        DEMO_PRODUCT_INFO
    HAVING
        MAX(DEMO_PRODUCT_INFO.LIST_PRICE) 
        = (SELECT MAX(MAX(DEMO_PRODUCT_INFO.LIST_PRICE)) 
             FROM DEMO_PRODUCT_INFO 
            GROUP BY DEMO_PRODUCT_INFO.CATEGORY)
    GROUP BY
        DEMO_PRODUCT_INFO.CATEGORY) A
WHERE
    DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY
HAVING
    MIN(DEMO_PRODUCT_INFO.LIST_PRICE) 
    = MIN((SELECT MIN(DEMO_PRODUCT_INFO.LIST_PRICE)
        FROM DEMO_PRODUCT_INFO 
       WHERE DEMO_PRODUCT_INFO.CATEGORY = A.CATEGORY))
GROUP BY
    DEMO_PRODUCT_INFO.PRODUCT_NAME

如何让这个SQL查询在第一路上工作？

2 个答案: