Question

我正在尝试创建一个查询，该查询返回typeID为1的所有商品的总数和所有类型ID为2的商品以及typeID为3的所有商品

我不确定我是否在正确的路线上，但我已经想出了这个

SELECT a.Atotal, b.Btotal, c.Ctotal, u.userID, t.typeID 
FROM 
    (SELECT ul.userID, COUNT( ul.listingID ) AS Atotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =1
        GROUP BY ul.userID
    )AS a,
    (SELECT ul.userID, COUNT( ul.listingID ) AS Btotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =2
        GROUP BY ul.userID
    )AS b,
    (SELECT ul.userID, COUNT( ul.listingID ) AS Ctotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =3
        GROUP BY ul.userID
    )AS c,
FROM tbl_users AS u
WHERE u.userID =1

毫不奇怪，它在第21行引发了例外

它说＃1064你的mysql语法中有错误检查手册blah de blah near＆＃39; FROM tbl_users AS u WHERE u.userID = 1＆＃39; AT LINE 21

有人可以帮我理解我哪里出错了，如果这是达到我想要的结果的最佳方法

非常感谢

Answer 1

您错过了子查询之间的JOIN语句。此外，您不能拥有两个FROM条款。并且你错过了加入条件。

SELECT a.Atotal, b.Btotal, c.Ctotal, u.userID, t.typeID 
FROM users AS u
JOIN (SELECT ul.userID, COUNT( ul.listingID ) AS Atotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =1
        GROUP BY ul.userID
    )AS a ON u.userID = a.userID
JOIN (SELECT ul.userID, COUNT( ul.listingID ) AS Btotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =2
        GROUP BY ul.userID
    )AS b ON u.userID = b.userID
JOIN (SELECT ul.userID, COUNT( ul.listingID ) AS Ctotal
        FROM tbl_user_listing AS ul
        LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
        WHERE t.typeID =1
        GROUP BY ul.userID
    )AS c ON u.userID = c.userID
WHERE u.userID =1

但是，最好将子查询合并为一个查询：

SELECT SUM(t.typeID = 1) AS Atotal, SUM(t.typeID = 2) AS Btotal, SUM(t.typeID = 3) AS Ctotal,
        u.userID, t.typeID
FROM users AS u
JOIN tbl_user_listing AS ul ON ul.userID = u.userID
LEFT JOIN tbl_listing_type AS t ON ul.listingID = t.listingID
WHERE u.userID = 1

我猜测t.typeID = 1是原始c子查询中的拼写错误。

我的mysql查询根据多个子句返回多个总计会引发异常

1 个答案: