在幾千條記錄里,存在著些相同的記錄,如何能用SQL語句,刪除掉重復的呢

1、查找表中多余的重復記錄，重復記錄是根據單個字段(peopleId)來判斷SELECT

*FROM

peopleWHERE

peopleId?IN?(

SELECT

peopleId

FROM

people

GROUP?BY

peopleId

HAVING

count(peopleId)?>?1

)

2、刪除表中多余的重復記錄，重復記錄是根據單個字段(peopleId)來判斷，只留有rowid最小的記錄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、查找表中多余的重復記錄(多個字段)SELECT

*FROM

vitae?aWHERE

(a.peopleId,?a.seq)?IN?(

SELECT

peopleId,

seq

FROM

vitae

GROUP?BY

peopleId,

seq

HAVING

count(*)?>?1

)

4、刪除表中多余的重復記錄(多個字段)，只留有rowid最小的記錄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、查找表中多余的重復記錄(多個字段)，不包含rowid最小的記錄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.消除一個字段的左邊的第一位：UPDATE?tableNameSET?[?Title?]=?RIGHT?([?Title?],(len([?Title?])?-?1))WHERE

Title?LIKE?'村%'

7.消除一個字段的右邊的第一位：UPDATE?tableNameSET?[?Title?]=?LEFT?([?Title?],(len([?Title?])?-?1))WHERE

Title?LIKE?'%村'

8.假刪除表中多余的重復記錄(多個字段)，不包含rowid最小的記錄UPDATE?vitaeSET?ispass?=-?1WHERE

peopleId?IN?(

SELECT

peopleId

FROM

vitae

GROUP?BY

peopleId

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