交叉连接左连接计数行

时间:2017-06-06 08:05:28

标签: mysql sql database join

我有这些表格:

任务组表

id name 1 cooking 2 baking

任务状态表

id name 1 open 2 done? 3 completed 4 re-open 5 suspend

任务表

project_id task_group_id task_status_id task_name 1 1 1 cooking martabak 1 1 2 cooking sate kambing 1 1 3 cooking nasi uduk 1 1 4 cooking nasi goreng 1 1 1 cooking martabak telor 1 1 2 cooking sate ayam 1 1 5 cooking nasi tutug oncom 1 1 5 cooking nasi pera 1 2 1 bake nastar 1 2 2 bake bolu pisang 1 2 3 bake bika ambon 1 2 5 bake bolu kukus 1 2 3 bake cheese stik 1 2 1 bake bolu ketan 1 2 5 bake papais 1 2 1 bake boled

结果我想要的是这样的:

project task_group task_status number Restaurant Cooking Completed 1 Restaurant Cooking Done? 2 Restaurant Cooking Open 2 Restaurant Cooking Re-open 1 Restaurant Baking Completed 2 Restaurant Baking Done? 1 Restaurant Baking Open 3 Restaurant Baking Re-open 0

排除任务状态“暂停”

我试图使用子查询与任务状态表交叉加入任务状态表,其中where子句task_status.name('打开','完成?','完成','重新打开'),但我不能得到正确的计数聚合

1 个答案:

答案 0 :(得分:1)

我认为你可以这样做:

SELECT
    project.name AS project,
    Task_Group.name as task_group ,
    Task_Status.name as task_status,
    COUNT(*) AS number
FROM
    Tasks
    JOIN Task_Group
        ON Tasks.task_group_id = Task_Group.id
    JOIN Task_Status
        ON Task.task_status_id=Task_Status.id
    JOIN project_table
        ON Task.project_id=project_table.project_id
WHERE 
    Task_Status.Id IN(1,2,3,4)
GROUP BY
    project_table.name,
    Task_Group.name,
    Task_Status.name
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