How to add trigger for my tables?

I have three tables, and the situation is we insert the values to table1 and table 2 from one asp page at the same time, and we want the table 3 has the primary key values(ID) of table 1 and 2's new rows after table 1 and 2 inserted. How should I achieve this? If trigger is the way to do, could anyone give some detailed code for this. Thanks very much!

table1

ID col1 col2...... Cus_ID datetime
.. .... .... ....
2 x xx A 12:12
... ... ... ...
7 z zz A 12:13

table 2

ID col1 col2..... Cus_ID datetime
.... .... ..... ....
3 x xx A 12:12
.. ... ... ...
4 yy y A 12:13

table 3
ID table1 table2 Cus_ID datetime
... .... ... ....
6 ( 2 ) ( 3 ) A 12:12
... .... ... ...
9 7 4 A 12:13

Right off the bat: why not combine table 1 and 2 into 1 new table?

A trigger is related to one table and the data modification statements (insert, delete, update).

A trigger have no visibility on which row in another table is inserted. Therefore I do not think triggers will work in this situation. But I could be mistaken..

Therefore, I think that you need to do the insert in tables 1 and 2 in a combined stored procedure together with capturing the ID values and the table 3 insert.

Hope this helps

Hello, I think your idea is good. But could u give some detailed explanation about the coding. I am new to this kind of thing. So need some more info. Thanks again and wait for your reply!

table 1 and 2 share the CustomerID and the date_time fields.

So the new table has those, together will all the other fields from table 1 and 2

Now you can create the trigger.
http://www.devarticles.com/art/1/36 for more information on how to use triggers.