首页 / 数据库 / MySQL / MySQL中删除重复数据只保留一条
用SQL语句,删除掉MySQL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,重复记录是根据单个字段(peopleId)来判断SELECT*FROMpeopleWHEREpeopleId IN (SELECTpeopleIdFROMpeopleGROUP BYpeopleIdHAVINGcount(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DELETEFROMpeopleWHEREpeopleName IN (SELECTpeopleNameFROMpeopleGROUP BYpeopleNameHAVINGcount(peopleName) > 1)AND peopleId NOT IN (SELECTmin(peopleId)FROMpeopleGROUP BYpeopleNameHAVINGcount(peopleName) > 1)3、查找表中多余的重复记录(多个字段)SELECT*FROMvitae aWHERE(a.peopleId, a.seq) IN (SELECTpeopleId,seqFROMvitaeGROUP BYpeopleId,seqHAVINGcount(*) > 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DELETEFROMvitae aWHERE(a.peopleId, a.seq) IN (SELECTpeopleId,seqFROMvitaeGROUP BYpeopleId,seqHAVINGcount(*) > 1)AND rowid NOT IN (SELECTmin(rowid)FROMvitaeGROUP BYpeopleId,seqHAVINGcount(*) > 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*FROMvitae aWHERE(a.peopleId, a.seq) IN (SELECTpeopleId,seqFROMvitaeGROUP BYpeopleId,seqHAVINGcount(*) > 1)AND rowid NOT IN (SELECTmin(rowid)FROMvitaeGROUP BYpeopleId,seqHAVINGcount(*) > 1)6.消除一个字段的左边的第一位:UPDATE tableNameSET [ Title ]= RIGHT ([ Title ],(len([ Title ]) - 1))WHERETitle LIKE "村%"7.消除一个字段的右边的第一位:UPDATE tableNameSET [ Title ]= LEFT ([ Title ],(len([ Title ]) - 1))WHERETitle 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 vitaeSET ispass =- 1WHEREpeopleId IN (SELECTpeopleIdFROMvitaeGROUP BYpeopleId本文永久更新链接地址