0

我很难做到这一点。

我有一个名为 1_related 的表

id,prod_pack,fk_prod_pack_id,fk_prod_pack_related,fk_prod_pack_related_id
'2', '0', '102', '0', '2482'
'3', '0', '102', '0', '3147'
'2294', '0', '102', '1', '10'

我还有另外 2 个表，分别称为 1_products 和 1_packages

我想根据 fk_prod_pack_related 的值加入任一表的内容（0 表示 1_products 表，1 表示 1_packages 表）

此查询从 1_related 返回第 2 行和第 3 行，并连接 1_products 的内容

SELECT 
    r . *, p . *
FROM
    1_related AS r
        INNER JOIN
    1_products as p ON r.fk_prod_pack_related_id = p.id
        and r.fk_prod_pack_related = 0
WHERE
    r.prod_pack = 0
        and r.fk_prod_pack_id = 102

但我也需要来自 1_packages 的数据，所以我尝试了这个，但它什么也没返回

SELECT 
    r . *, p . *, s . *
FROM
    1_related AS r
        INNER JOIN
    1_products as p ON r.fk_prod_pack_related_id = p.id
        and r.fk_prod_pack_related = 0
        INNER JOIN
    1_packages as s ON r.fk_prod_pack_related_id = s.id
        and r.fk_prod_pack_related = 1
WHERE
    r.prod_pack = 0
        and r.fk_prod_pack_id = 102
4

1 回答 1

1

您需要左外连接，因为只有一个查询会匹配：

SELECT 
    r . *, p . *, s . *
FROM
    1_related AS r
        left outer JOIN
    1_products as p ON r.fk_prod_pack_related_id = p.id
        and r.fk_prod_pack_related = 0
        left outer JOIN
    1_packages as s ON r.fk_prod_pack_related_id = s.id
        and r.fk_prod_pack_related = 1
WHERE
    r.prod_pack = 0
        and r.fk_prod_pack_id = 102
于 2013-01-24T16:30:18.220 回答