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help!!! who's familiar with mysql command

help!!! who's familiar with mysql command# Database - 数据库

t*g2006-10-06 07:10

1 楼

I have 2 sets of data that stored in mysql as table A and B. both have 2
field : GI(primary key) and Function in the table. I tried the command:
Select A.GI from A,B where A.GI=B.GI; and got the
data that has A and B in common.
but How could I compare this 2 tables and get the data that just included in
A but not in B? the command: Select A.GI from A,B where A.GI != B.GI; didn'
t work.
please help me out! thanks

w*r2006-10-06 07:10

2 楼

select a.gi, b.gi
from a left join b on (a.gi = b.gi)
where b.gi is null;

in
didn'

【在 t*******g 的大作中提到】

: I have 2 sets of data that stored in mysql as table A and B. both have 2
: field : GI(primary key) and Function in the table. I tried the command:
: Select A.GI from A,B where A.GI=B.GI; and got the
: data that has A and B in common.
: but How could I compare this 2 tables and get the data that just included in
: A but not in B? the command: Select A.GI from A,B where A.GI != B.GI; didn'
: t work.
: please help me out! thanks