OneToMany關係。如何提出要求？

Question

你好。我是SQL中的noob，所以將appriciate，如果你幫我寫一個SQL請求獲取FINALSCORE字段FROM tennisset表，與tennismatch相關WHERE id = 1

謝謝。

Answer 1

嘗試此查詢：

select FINALSCORE from 
tennismatch join 
tennismatch_tennisset on tennismatch.ID = tennismatch_tennisset.TennisMatch_ID and tennismatch.ID = 1 join 
tennisset on tennismatch_tennisset.mapOfSets_ID = tennisset.ID 

從表「tennismatch」刪除記錄，首先刪除子表「tennismatch_tennisset」的記載。

嘗試這樣：

delete from tennismatch_tennisset where TennisMatch_ID =1 
delete from tennismatch where id=1 

Answer 2

您需要使用表之間的連接。在你的情況下，它必須通過tenismatch_tenisset這是兩者之間的綁定表完成。

select finalscore from tennismatch m 
join tenismatch_tennisset ms 
    on m.id = ms.tennismatch_id 
join tennisset s 
    on ms.mapofsets_id = s.id 
where m.id = 1