題目
題目難度:簡單
編寫一個 SQL 查詢,來刪除 Person 表中所有重複的電子郵箱,重複的郵箱裏只保留 Id 最小 的那個。
Id | |
---|---|
1 | [email protected] |
2 | [email protected] |
3 | [email protected] |
例如,在運行你的查詢語句之後,上面的 Person 表應返回以下幾行:
Id | |
---|---|
1 | [email protected] |
2 | [email protected] |
解題
代碼
DELETE p1
FROM Person as p1 , person as p2
where p1.Email=p2.Email and p1.Id>p2.Id