Re: How to find a duplicate record in Ac - 未名空间MITBBS历史存档

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Re: How to find a duplicate record in Ac

Re: How to find a duplicate record in Ac# Database - 数据库

x*n2003-12-24 08:12

1 楼

Suppose the primary key you wanna set is MyTable.ColumnA
Then
SELECT MAX(Duplicates), ColumnA
FROM
( SELECT COUNT(*) AS Duplicates, ColumnA
FROM MyTable
GROUP BY ColumnA);

b*e2003-12-24 08:12

2 楼

maybe this would be better
select count(*) as dup, columnA from myTable group by ColumnA
having dup>1

【在 x***n 的大作中提到】

: Suppose the primary key you wanna set is MyTable.ColumnA
: Then
: SELECT MAX(Duplicates), ColumnA
: FROM
: ( SELECT COUNT(*) AS Duplicates, ColumnA
: FROM MyTable
: GROUP BY ColumnA);

c*t2003-12-24 08:12

3 楼

Why need nested w-c?
select count(*), ColumnA
from TABLE
group by ColumnA
having count(*) > 1

【在 x***n 的大作中提到】

: Suppose the primary key you wanna set is MyTable.ColumnA
: Then
: SELECT MAX(Duplicates), ColumnA
: FROM
: ( SELECT COUNT(*) AS Duplicates, ColumnA
: FROM MyTable
: GROUP BY ColumnA);