mysql - 如果下一行与当前行具有相同的 first_name，则删除行

Question

我在 MySql 中有一个用户表，如果下一行具有相同的 first_name，我需要编写将删除行的查询。

Answer 1

假设您有这样的表，并且您想删除第二条记录，因为第二条和第三条记录的名称相同。（基兰）

+-----+-----------+-------------+------------+---------------------------+
| ID  |   Name    |    DoB      |  Address   |           Email           |
+-----+-----------+-------------+------------+---------------------------+
|  1  | Ramesh    | 1990-12-30  | Indore     | Ramesh@gmail.com          |
|  2  | Khilan    | 1990-12-12  | Ottawa     | Khilan@gmail.com          |  > Name: Khilan
|  3  | Khilan    | 1992-02-02  | New York   | KhilanNY@gmail.com        |  > Name: Khilan
|  4  | Miriam    | 1990-05-12  | Milwaukee  | MiriamRSeyler@armyspy.com |
|  5  | Mary      | 1993-12-23  | Milwaukee  | dee.robel1976@hotmail.com |
|  6  | Elaine    | 1980-01-20  | Memphis    | kimberly2004@yahoo.com    |
|  7  | Margaret  | 1992-02-12  | Minnesota  | concepcjaskols@yahoo.com  |
|  8  | Khilan    | 1992-03-14  | New York   | KhilanNY@gmail.com        |
+-----+-----------+-------------+------------+---------------------------+
PRIMARY KEY: ID

然后你可以使用这个查询来做到这一点。

DELETE FROM TableName
WHERE  id IN (SELECT id
              FROM   (SELECT t1.id AS id
                      FROM   TableName t1
                             LEFT JOIN TableName t2
                                    ON t1.id = t2.id - 1
                      WHERE  t1.name = t2.name) tmp)  

如果 ID 序列中存在间隙，请改用此查询。

DELETE FROM person
WHERE  id IN (SELECT id
              FROM   (SELECT t1.id
                      FROM   (SELECT *,
                                     Row_number() OVER (ORDER BY id) AS RN
                              FROM   person) t1
                             LEFT JOIN (SELECT *,
                                               Row_number() OVER (ORDER BY id) AS RN
                                        FROM   person) t2
                                    ON t1.rn = t2.rn - 1
                      WHERE  t1.NAME = t2.NAME
                      ORDER  BY t1.id) tmp)  

删除后的输出 ( SELECT * FROM TableName)

+-----+-----------+-------------+------------+---------------------------+
| ID  |   Name    |    DoB      |  Address   |           Email           |
+-----+-----------+-------------+------------+---------------------------+
|  1  | Ramesh    | 1990-12-30  | Indore     | Ramesh@gmail.com          |
|  3  | Khilan    | 1992-02-02  | New York   | KhilanNY@gmail.com        |
|  4  | Miriam    | 1990-05-12  | Milwaukee  | MiriamRSeyler@armyspy.com |
|  5  | Mary      | 1993-12-23  | Milwaukee  | dee.robel1976@hotmail.com |
|  6  | Elaine    | 1980-01-20  | Memphis    | kimberly2004@yahoo.com    |
|  7  | Margaret  | 1992-02-12  | Minnesota  | concepcjaskols@yahoo.com  |
|  8  | Khilan    | 1992-03-14  | New York   | KhilanNY@gmail.com        |
+-----+-----------+-------------+------------+---------------------------+

在线演示：https ://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=6510a3a610e83d27a8d4dc43aeeb3be7