Question

我正在寻找一种按状态分组数据的方法。我有一个简单的选择，只是为了演示：

MS SQL Server 2014架构设置：

CREATE TABLE Projects ([ID] int, [Project] varchar(10));
INSERT INTO Projects ([ID], [Project])
VALUES
    (1, 'Admin'),
    (2, 'Accounts'),
    (3, 'Finance')
;

CREATE TABLE Tasks ([ID] int, [ProjectID] int, [Task] int, [Status] varchar(8));
INSERT INTO Tasks
    ([ID], [ProjectID], [Task], [Status])
VALUES
    (1, 1, '001', 'Open'),
    (2, 1, '002', 'Canceled'),
    (3, 1, '003', 'Canceled'),
    (4, 1, '004', 'Canceled'),
    (5, 2, '005', 'Rejected'),
    (6, 2, '006', 'Canceled'),
    (7, 2, '007', 'Canceled'),
    (8, 3, '008', 'Canceled'),
    (9, 3, '009', 'Canceled'),
    (10, 3, '010', 'Canceled'),
    (11, 3, '011', 'Canceled'),
    (12, 3, '0012', 'Rejected')
;

查询1 ：

SELECT
  Projects.Project,
  COUNT(Tasks.Status) AS Total
FROM
  Projects
  LEFT JOIN Tasks ON Projects.ID = Tasks.ProjectID
 GROUP BY
   Projects.Project

Results ：

|  Project | Total |
|----------|-------|
| Accounts |     3 |
|    Admin |     4 |
|  Finance |     5 |

但我正在寻找一种输出方法：

|  Project | Open | Canceled | Rejected |
|----------|------|----------|----------|
|    Admin |    1 |        3 |          |
| Accounts |      |        2 |        1 |
|  Finance |      |        4 |        1 |

所需结果按任务状态对项目进行分组。我怎样才能做到这一点？感谢。

Answer 1

您可以使用条件聚合：

SELECT
    Projects.Project
  , [Open]   = count(case when tasks.status='open' then 1 end)
  , Canceled = count(case when tasks.status='Canceled ' then 1 end)
  , Rejected = count(case when tasks.status='Rejected ' then 1 end)
  , Total = COUNT(Tasks.Status)
FROM
  Projects
  LEFT JOIN Tasks ON Projects.ID = Tasks.ProjectID
 GROUP BY
   Projects.Project

小提琴：http://sqlfiddle.com/#!6/4b862/4/0

返回：

+----------+------+----------+----------+-------+
| Project  | Open | Canceled | Rejected | Total |
+----------+------+----------+----------+-------+
| Accounts |    0 |        2 |        1 |     3 |
| Admin    |    1 |        3 |        0 |     4 |
| Finance  |    0 |        4 |        1 |     5 |
+----------+------+----------+----------+-------+

Answer 2

您可以使用此查询。

SELECT * FROM 
(
    SELECT
      Projects.Project,
      Tasks.Status
    FROM
      Projects
      LEFT JOIN Tasks ON Projects.ID = Tasks.ProjectID
) Src 
    PIVOT (COUNT(Status) FOR Status IN ([Open] ,[Canceled],[Rejected])) P

结果：

Project    Open        Canceled    Rejected
---------- ----------- ----------- -----------
Accounts   0           2           1
Admin      1           3           0
Finance    0           4           1

SQL Group By状态

2 个答案: