SQL：獲取的行數，其中ID在參考表

Question

我有兩個表匹配ID：

• bid_tag

• bid_tag_design

  bid_tag： ID，tag_design，tag_size，USER_ID ，保留

  big_tag_design： id，name

我希望能夠查詢多少標籤設計有各自的bid_tag表WHERE user_id = 0 AND reserved = 0

內的話，我將使用查詢來創建一個CRON工作的庫存水平的每日報告...

Answer 1

在您的評論之後，似乎表格之間的鏈接是相反的。所以我改變了查詢採取的架構考慮，它應該與這個合作：

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 

讓我們假設你在bid_tag_design有這樣的：

id | name 
1 | design 1 
2 | design 2 

然後這bid_tag

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 

然後第二個查詢的結果應該是

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

Answer 2

如果你只想計數，而不是按標籤數量，然後是這樣的：

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

做它，假設USER_ID和保留在該表。你只需要當bid_tag有一個或兩個領域，類似的加入：

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 

如果你想爲每個設計一排，然後組由：

select btd.bid_tag_design_id, count(*) 

從bid_tag BT加盟上bt.bid_tag_id = btd.bid_tag_id 其中bt.user_id = 0 bid_tag_design BTD 和btd.reserved = 0

Answer 3

嘗試此

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