Question

我有两张桌子：

bid_tag
bid_tag_design

bid_tag： id，tag_design，tag_size，user_id，reserved

big_tag_design： id，name

我希望能够在bid_tag表WHERE user_id = 0 AND reserved = 0

中查询每个标签设计的数量。

然后，我将使用该查询为每日库存水平报告创建CRON作业...

Answer 1

如果您只想要计数而不是按标记计数，那么就像：

select count(*)
from bid_tag_design
where user_id = 0 and reserved = 0

这样做，假设user_id和reserved在该表中。如果bid_tag包含以下一个或两个字段，您只需要加入，例如：

select count(*)
from bid_tag bt join
     bid_tag_design btd
     on bt.bid_tag_id = btd.bid_tag_id
where bt.user_id = 0 and btd.reserved = 0

如果您想为每个设计添加一行，请按以下方式分组：

select btd.bid_tag_design_id, count(*)

来自bid_tag bt join bid_tag_design btd 在bt.bid_tag_id = btd.bid_tag_id 其中bt.user_id = 0且btd.reserved = 0

Answer 2

在您的评论之后，似乎表之间的链接是另一种方式。所以我更改了查询以考虑模式，它应该使用这个：

SELECT COUNT(*) as nbDesigns, bid_tag_design.id, bid_tag_design.name
FROM bid_tag_design
  LEFT JOIN bid_tag ON bid_tag.tag_design = bid_tag_design.id
WHERE bid_tag.user_id = 0 AND bid_tag.reserved = 0
GROUP BY bid_tag.tag_design

让我们说你在bid_tag_design中有这个：

id | name
1  | design 1
2  | design 2

然后在bid_tag

中

id | tag_design | user | reserved
1  | 1          | 0    | 0
2  | 1          | 0    | 0
3  | 2          | 0    | 0
4  | 2          | 0    | 0
5  | 1          | 1    | 0
6  | 2          | 2    | 0
7  | 1          | 0    | 0
8  | 1          | 0    | 0
9  | 1          | 3    | 0

然后第二个查询的结果应该是

nbDesigns | id | name
4         | 1  | design 1
2         | 2  | design 2

Answer 3

试试这个

     select tag_design ,count(tag_design) countdesign
     from bid_tag
     where user_id = 0 and reserved = 0
     group by tag_design

SQL：获取ID与引用表中的ID匹配的行数

3 个答案: