mysql如何去重复记录

SELECT DISTINCT column1, column2, ...
FROM table_name;

SELECT column1, column2, COUNT(*)
FROM table_name
GROUP BY column1, column2
HAVING COUNT(*) > 1;

DELETE t1 FROM table_name t1
INNER JOIN (
    SELECT column1, column2, MIN(id) as min_id
    FROM table_name
    GROUP BY column1, column2
    HAVING COUNT(*) > 1
) t2 ON t1.column1 = t2.column1 AND t1.column2 = t2.column2 AND t1.id > t2.min_id;

CREATE TEMPORARY TABLE temp_table AS
SELECT column1, column2, MIN(id) as min_id
FROM table_name
GROUP BY column1, column2
HAVING COUNT(*) > 1;

DELETE FROM table_name
WHERE id NOT IN (SELECT min_id FROM temp_table);

DROP TEMPORARY TABLE temp_table;