Question

两张桌子，brand_gifts bg，giftcode gc：

表1：brand_gifts

id brand_id name

表2：礼品代码

id gift_id code usesleft

我用来检索数据的值是brand_gifts表中的brand_id。我需要的是一个元素列表，在表一brand_id = 1，这两个表由table1相关：id table2：gift_id（不是必需的，table1上的所有元素都与table2有关系，换句话说，不是所有的ID来自表一有table2上的gift_id，所以使用该关系我想查询所有brand_id = 1，其中也使用左边＆gt; 0.

我试过了：

SELECT gc.gift_id
FROM brand_gifts bg, giftcode gc
WHERE (
bg.brand_id =1
AND gc.gift_id = gc.id
AND gc.usesleft >0
)
LIMIT 0 , 30

但结果是错误的。

Answer 1

试试这个

SELECT gc.gift_id
FROM brand_gifts bg, giftcode gc
WHERE (
bg.brand_id =1
AND gc.gift_id = bg.id
AND gc.usesleft >0
)
LIMIT 0 , 30

Answer 2

   SELECT gc.gift_id
    FROM brand_gifts bg, giftcode gc
   WHERE (
    bg.brand_id =1
    AND gc.gift_id = gc.id    <==
   AND gc.usesleft >0
   )
    LIMIT 0 , 30

您的错误在标记的行中显示，条件应为“gc.gift_id = bg.id”

   SELECT gc.gift_id
    FROM brand_gifts bg, giftcode gc
   WHERE (
    bg.brand_id =1
    AND gc.gift_id = bg.id    <==
   AND gc.usesleft >0
  )
    LIMIT 0 , 30

Answer 3

试

SELECT gc.gift_id
FROM giftcode gc
LEFT JOIN brand_gifts bg
ON gc.gift_id = bg.id
WHERE gc.usesleft > 0

关于mySql的JOIN问题

3 个答案: