mysql查询使用单个查询检索计数

Question

我在执行以下查询时得到以下结果：

select * from db1.user_details;

Dept_Id     Form_Id     Status
-----------------------------------------------
dept1       Form1       CD1
dept1       Form2       CD1
dept1       Form3       CD2
dept2       Form1       CD1
dept3       Form3       CD2
dept3       Form1       CD1
dept3       Form2       CD3
----------------------------------------------

CD1是＆＃34;收到＆＃34;，CD2是＆＃34;在处理＆＃34;，CD3是＆＃34;拒绝＆＃34;。

现在我想找出每个部门的收到，正在处理和拒绝的总数

结果应该是：

Dept_Id Received    In Process  Rejected
-------------------------------------------------------------
dept1       2       1             0
dept2       1       0             0
dept3       1       1             1
-------------------------------------------------------------

我无法为此编写mysql查询。任何帮助都非常值得赞赏。

Answer 1

您可以使用SUM()条件来获取计数，使用SUM中的条件将导致布尔值，您可以获得计数

select Dept_Id,
SUM(`Status`='CD1') Received,
SUM(`Status`='CD2') In_Process,
SUM(`Status`='CD3') Rejected
from Table1
GROUP BY Dept_Id

Fiddle

Answer 2

SELECT Dept_Id,,
    SUM(status = 'CD1') as Received,
    SUM(status = 'CD2') as In_Process,
    SUM(status = 'CD3') as Rejected
FROM 
    tablneme
GROUP BY Dept_Id

SQL FIDDLE

Answer 3

使用IF控制流语句，如下所示：

SELECT Dept_Id,
  SUM(IF(Status='CD1', 1, 0)) AS Received, 
  SUM(IF(Status='CD2', 1, 0)) AS InProcess,
  SUM(IF(Status='CD3', 1, 0)) AS Rejected
FROM db1.user_details
GROUP BY Dept_Id