從第三張表中檢索數據

Question

這個問題讓人討厭，因爲我還沒有在sql中使用中間表的煩惱。但是，我在一時間趕時間，所以我選擇反問。

我希望結合這些SQL代碼，這樣我就可以在同一個轉發器中從「老師」以及「團隊」和「級別」中檢索數據。

我是從「老師」表通過FK_teacher從middletable「teacher_team」這是通過FK_team與我的球隊表醒目的名稱

難道任何機會有可能這些所謂聯合，我可以通過一箇中繼器提取它？

// Team <-> level relation 

SELECT 
team.team_id as team_id, 
level.level as level, 
FROM team 
INNER JOIN level ON level.level_id = team.team_FK_level 
WHERE team.team_FK_type = @id 


// Team <-> Team_Teacher <-> Teacher relation 

SELECT teacher.teacher_name as name 
FROM teacher WHERE teacher.teacher_id 
IN (
SELECT teacher_team.FK_teacher 
FROM teacher_team 
INNER JOIN team ON team.team_id = teacher_team.FK_team 
WHERE team.team_FK_type = @id 
) 

*編輯* 得到這個代碼的基礎上拉維·辛格的答案工作。我遇到了另一個問題。 如果在teacher_teams中有兩位教師與其相關（如果有），我的轉發器會輸出兩次隊伍。有沒有什麼辦法可以合併這些，而不需要在中繼器內部建立中繼器？

SELECT 
team.team_id as team_id, 
level.level as level, 
teacher_team.FK_teacher, 
teacher.teacher_name as teacher 
FROM team 
INNER JOIN level ON level.level_id = team.team_FK_level 
LEFT JOIN teacher_team on teacher_team.FK_hold = team.team_id 
LEFT JOIN teacheron teacher.teacher_id = teacher_team.FK_teacher 
WHERE team.team_FK_type = @id 

Answer 1

試試這個：

SELECT 
teacher.teacher_name as name 
,team.team_id as team_id 
,level.level as level 
FROM teacher 
inner join teacher_team on teacher.teacher_id =teacher_team.FK_teacher 
INNER JOIN team ON team.team_id = teacher_team.FK_team 
INNER JOIN level ON level.level_id = team.team_FK_level 
WHERE team.team_FK_type = @id 

更新： 這應該與您更新的問題有所幫助：

with demo_cte as(
SELECT 
teacher.teacher_name as name 
,team.team_id as team_id 
,level.level as level 
FROM teacher 
inner join teacher_team on teacher.teacher_id =teacher_team.FK_teacher 
INNER JOIN team ON team.team_id = teacher_team.FK_team 
INNER JOIN level ON level.level_id = team.team_FK_level 
WHERE team.team_FK_type = @id 
) 


select distinct t1.team_id, 
    t1.level, 
    STUFF(
     (SELECT ', ' + t2.name 
      FROM demo_cte t2 
      where t1.team_id = t2.team_id 
      and t1.level = t2.level 

      FOR XML PATH ('')) 
      , 1, 1, '') AS name 
from demo_cte t1;