mysql左联接返回意外行数 [英] mysql left join returns unexpected amount of rows

问题描述

我有2张桌子，

tableA has 41 rows

和

tableB has 3 rows

我正在尝试通过使用左联接的查询来获取这2个表的总行，但是我得到的行数(123)比预期的多(44)

I am trying to get the total rows of these 2 tables via a query using left join but i get way more rows(123) than expected(44)

查询:

SELECT COUNT(*)
    FROM tableA as u
LEFT JOIN tableB as d
    ON u.uid=d.uid
WHERE
    u.uid=912391178669
    AND
    u.deleted = 0
    AND
    d.deleted=0

表架构:

表A

id | uid |删除

id | uid | deleted

表B

id | uid |删除

id | uid | deleted

推荐答案

我已经运行了以下查询，它运行正常..U可以将其检出.

I have run the following query It is working correctly.. U can check it out.

SELECT 
  ( SELECT count(*) from table1 where.... )
+ ( SELECT count(*) from table2 where.... )
as total from dual

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