Well..thanks for all of you. Your responses are important and help me very much.

Hi noeld,

Thanks for the response..but there is NOT necessary having equal date..it just simply put both column side by side.

yes..it can have a primary key for each table..but there is NO direct relation between both primary keys.

Let's say :

Table A : 

ID RegDate

1 2005/1/15

2 2005/1/16

3 2005/1/18

4 2005/1/20

Table B : ...