求教:数据操作 - 未名空间MITBBS历史存档

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求教:数据操作

求教:数据操作# Database - 数据库

z*a2004-05-26 07:05

1 楼

想在DB2中实现以下数据操作，不知道是否有相应的Statement or Function:
Table A has 2 columns: c1 and c2. c1 already has data populated. c2 is empty.
I need to populate c2 with c1's data only when there's no duplicates. For
example: c1 has {a,a,b,c,c,d,e}. After running the SQL statement, c2 should be
populated with {"","",b,"","",d,e}. Is there any way to accomplish this?
Thanks for your help!

c*g2004-05-26 07:05

2 楼

open a cursor.

【在 z****a 的大作中提到】

: 想在DB2中实现以下数据操作，不知道是否有相应的Statement or Function:
: Table A has 2 columns: c1 and c2. c1 already has data populated. c2 is empty.
: I need to populate c2 with c1's data only when there's no duplicates. For
: example: c1 has {a,a,b,c,c,d,e}. After running the SQL statement, c2 should be
: populated with {"","",b,"","",d,e}. Is there any way to accomplish this?
: Thanks for your help!

aw2004-05-26 07:05

3 楼

没必要。
INSERT INTO T2
SELECT
CASE
WHEN value IN (SELECT value FROM T1 GROUP BY value HAVING COUNT(id)=1) THEN
value
ELSE ''
END
FROM
T1

empty.
should be

【在 c**g 的大作中提到】

: open a cursor.