sql怎么删除重复数据

SELECT DISTINCT column_name1, column_name2
FROM table_name;

DELETE FROM table_name
WHERE (column_name1, column_name2) IN (
  SELECT DISTINCT column_name1, column_name2
  FROM table_name
);

create table my_table (
  id int not null auto_increment primary key,
  name varchar(255) not null,
  email varchar(255) not null
);

insert into my_table (name, email) values ('John Doe', 'john.doe@example.com');
insert into my_table (name, email) values ('John Doe', 'john.doe@example.com');
insert into my_table (name, email) values ('Jane Smith', 'jane.smith@example.com');
insert into my_table (name, email) values ('Jane Smith', 'jane.smith@example.com');

DELETE FROM my_table
WHERE (name, email) IN (
  SELECT DISTINCT name, email
  FROM my_table
);

select * from my_table;

| id | name | email |
| --- | --- | --- |
| 1 | John Doe | john.doe@example.com |
| 3 | Jane Smith | jane.smith@example.com |