MySQL中删除重复数据只保留一条

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，重复记录是根据单个字段（peopleId）来判断

SELECT
    *FROM
    peopleWHERE
    peopleId IN (        SELECT
            peopleId        FROM
            people        GROUP BY
            peopleId        HAVING
            count(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        GROUP BY
            peopleName        HAVING
            count(peopleName) > 1
    )AND peopleId NOT IN (    SELECT
        min(peopleId)    FROM
        people    GROUP BY
        peopleName    HAVING
        count(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        GROUP BY
            peopleId,
            seq        HAVING
            count(*) > 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        GROUP BY
            peopleId,
            seq        HAVING
            count(*) > 1
    )AND rowid NOT IN (    SELECT
        min(rowid)    FROM
        vitae    GROUP BY
        peopleId,
        seq    HAVING
        count(*) > 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        GROUP BY
            peopleId,
            seq        HAVING
            count(*) > 1
    )AND rowid NOT IN (    SELECT
        min(rowid)    FROM
        vitae    GROUP BY
        peopleId,
        seq    HAVING
        count(*) > 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%'12341234

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'12341234

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 =- 1WHERE
    peopleId IN (        SELECT
            peopleId        FROM
            vitae        GROUP BY
            peopleId