Mysql 刪除重複記錄,保留id最大的記錄,參考SQL如下
DELETE tbl_exam FROM tbl_exam, ( SELECT max(tbl_id) id, studyid FROM tbl_exam GROUP BY studyid HAVING count( * ) > 1 ) t2 WHERE tbl_exam.studyid = t2.studyid AND tbl_exam.tbl_id < t2.id
Mysql 刪除重複記錄,保留id最大的記錄,參考SQL如下
DELETE tbl_exam FROM tbl_exam, ( SELECT max(tbl_id) id, studyid FROM tbl_exam GROUP BY studyid HAVING count( * ) > 1 ) t2 WHERE tbl_exam.studyid = t2.studyid AND tbl_exam.tbl_id < t2.id