sql查出重複數據，刪除重複數據只留一條（小白專用）

查表中多餘重複記錄，根據單個字段（username）來判斷 select username,count() as num from tusertest group by username having COUNT()>1 刪除重複 DELETE FROM tusertest WHERE id NOT IN (SELECT MIN(id) FROM tusertest GROUP BY userna

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