CROSS JOIN左連接數排

Question

我有這些表：

任務組表

id name 1 cooking 2 baking

任務狀態表

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

任務表

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

和結果我想是這樣的：

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

任務狀態 「暫停」 被排除

我已經嘗試過加入任務帶有任務狀態表的子表（使用where子句中的task_status.name（'open'，'done？'，'completed'，'re-open'）），但是我不能得到正確的計數聚集

Answer 1

我認爲你可以做這樣的事情：

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