MySQL中删除重复数据只保留一条
在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
1、查找表中多余的重复记录MySQL 处理重复数据,重复记录是根据单个字段(peopleId
用SQL语句,删除掉重复项只保留一条 在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢 1、查找表中多余的重复记录MySQL 处理重复数据,重复记录是根据单个字段(peopleId)来判断 SELECT*FROM peopleWHERE peopleId IN ( SELECT peopleId FROM people GROUPBY peopleId HAVINGcount(peopleId)>1 ) 2、删除表中多余的重复记录,重复记录是根据单个字段(peopleId)来判断,只留有rowid最小的记录 DELETEFROM peopleWHERE peopleName IN ( SELECT peopleName FROM people GROUPBY peopleName HAVINGcount(peopleName)>1 )ANDpeopleIdNOTIN ( SELECTmin(peopleId) FROM people GROUPBY peopleName HAVINGcount(peopleName)>1) 3、查找表中多余的重复记录(多个字段) SELECT*FROM vitae aWHERE (a.peopleId, a.seq) IN ( SELECT peopleId, seq FROM vitae GROUPBY peopleId, seq HAVINGcount(*)>1 ) 4、删除表中多余的重复记录(多个字段),只留有rowid最小的记录 DELETEFROM vitae aWHERE (a.peopleId, a.seq) IN ( SELECT peopleId, seq FROM vitae GROUPBY peopleId, seq HAVINGcount(*)>1 )ANDrowidNOTIN ( SELECTmin(rowid) FROM vitae GROUPBY peopleId, seq HAVINGcount(*)>1) 5、查找表中多余的重复记录(多个字段),不包含rowid最小的记录 SELECT*FROM vitae aWHERE (a.peopleId, a.seq) IN ( SELECT peopleId, seq FROM vitae GROUPBY peopleId, seq HAVINGcount(*)>1 )ANDrowidNOTIN ( SELECTmin(rowid) FROM vitae GROUPBY peopleId, seq HAVINGcount(*)>1) 6.消除一个字段的左边的第一位: UPDATE tableNameSET[ Title ]=RIGHT([ Title ],(len([ Title ])-1))WHERE Title LIKE'村%' 7.消除一个字段的右边的第一位: UPDATE tableNameSET[ Title ]=LEFT([ Title ],(len([ Title ])-1))WHERE Title LIKE'%村' 8.假删除表中多余的重复记录(多个字段),不包含rowid最小的记录 UPDATE vitaeSETispass=-1WHERE peopleId IN ( SELECT peopleId FROM vitae GROUPBY peopleId (编辑:航空爱好网) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |