mysql查找重复数据

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

SELECT t1.*
FROM table_name t1
JOIN (
    SELECT column1, column2
    FROM table_name
    GROUP BY column1, column2
    HAVING COUNT(*) > 1
) t2 ON t1.column1 = t2.column1 AND t1.column2 = t2.column2;

DELETE t1 FROM table_name t1
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 TABLE table_name (
    id INT AUTO_INCREMENT PRIMARY KEY,
    column1 VARCHAR(255),
    column2 VARCHAR(255),
    UNIQUE (column1, column2)
);