count与left join只显示一行

kse8i1jr  于 2021-06-17  发布在  Mysql
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我的数据库中有以下数据:
scu银行:

---------------------------------
|   id    |   type   |   name   |
|-------------------------------|  
|    1    |    1     |   One    |
|    2    |    1     |   Two    |
|    3    |    2     |  Three   |
|    4    |    3     |   Four   |
---------------------------------

scu声明:

---------------------------------
|   id    |   code   |    status    |
|-----------------------------------|  
|    1    |    1     |      0       |
|    2    |    1     |      1       |
|    3    |    2     |      0       |
|    4    |    1     |      0       |
-------------------------------------

我要做的是选择表中的所有行 scu_banks 然后计算我有多少行的状态为0。数据应表示为:

--------------------------------------------------------------
| scu_banks.type | scu_banks.name |   status  | scu_banks.id |
--------------------------------------------------------------
|       1        |      One       |     2     |      1       |
|       1        |      Two       |     0     |      2       | //There is no row with status 0
|       2        |     Three      |     0     |      3       |
|       3        |      Four      |     0     |      4       |
--------------------------------------------------------------

当我运行sql语句时,我得到以下数据:

---------------------------------------------------------------
| scu_banks.type | scu_banks.name |    status   | scu_banks.id |
--------------------------------------------------------------
|       1        |      One       |      2      |      1       |
---------------------------------------------------------------

我得到的数据是正确的。2它是表中所有行的总数 scu_statement . 语句也不显示数据库中的其他行。
有人知道我的sql语句有什么问题吗?
下面是我的sql语句:

SELECT b.type 'scu_banks.type',
b.name 'scu_banks.name',
count(y.status) 'status',
b.id 'scu_banks.id'
FROM scu_banks b
LEFT JOIN (SELECT s.code, count(s.status) status
           FROM scu_bankstatement s 
           WHERE status='0'
           GROUP BY s.code) y
           ON y.code = b.id
yeotifhr

yeotifhr1#

你需要一个 GROUP BY 在您的外部查询中,否则查询只计算所有银行的状态。您还可以通过 LEFT JOIN 在code/id和status=0的两个表中

SELECT b.type `scu_banks.type`,
b.name `scu_banks.name`,
COUNT(s.status) `status`,
b.id `scu_banks.id`
FROM scu_banks b
LEFT JOIN scu_statement s ON s.code = b.id AND s.status = 0
GROUP BY b.id, b.name, b.type

输出

scu_banks.type  scu_banks.name  status  scu_banks.id
1               One             2       1
1               Two             1       2
2               Three           0       3
3               Four            0       4

在dbfiddle上演示

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