刪除記錄在SQL Server上的外鍵

Question

我有3個表：

• 後
• 像表之間
• 評論

關係是：

• 郵寄表格：postid PK
• 如表：LikeID PK，帖子ID FK，CommentID FK
• 評語表：CommentID PK，帖子ID FK，CommentReplybyID FK（自連接上commentid）

現在我要刪除帖子表，但我交我得到一個錯誤。

我使用下面這個查詢：

begin tran 

declare @userid int = 68; 
declare @postid int = 15; 

delete from likes 
where postid = @postid and userid = @userid 

delete from comments 
where postid = @postid and userid = @userid 

delete from post 
where postid = @postid and userid = @userid 

rollback tran 

我得到這些錯誤：

消息547，級別16，狀態0，第8行
DELETE語句衝突以相同的表REFERENCE約束「Comments_fk3」。衝突發生在數據庫「development-topthat」，表「dbo.Comments」，列'CommentReplyID'。

Msg 547，Level 16，State 0，Line 9
DELETE語句與REFERENCE約束「Likes_fk1」衝突。衝突發生在數據庫「development-topthat」，表「dbo.Likes」，列'PostID'。

我需要幫助，我在哪裏做錯了。如何實現這一目標？

Answer 1

通過CommentReplyID的外觀和自我連接評論我懷疑你在評論表中有某種嵌套關係。

您需要刪除CommentReplyId與刪除註釋相匹配的記錄。

begin tran 

declare @userid int = 68; 
declare @postid int = 15; 

-- are you sure userid should be used here? 
delete from likes where postid = @postid and userid = @userid 

delete from comments c1 join comments c2 on c2.CommentReplyId = c1.CommentId where c1.postid = @postid and c1.userid = @userid 

delete from comments where postid =@postid and userid = @userid 

delete from post where postid = @postid and userid = @userid 

rollback tran