roboticus

Thanks for your reply, but in my case using UPDATE statement is not good, since the changed fields vary for different records, I mean for the 1st record, maybe the changed fields is the first 3 ones, but for the 2nd record, maybe the changed fields are the last 3 ones. It will be tedious to find out which fields have changed for each record and then write out an update statement.

For the 3 tables I have mentioned, the tbl_3 is almost a combine of the tbl_1 and tbl_2 on each primary key. Just like:

tbl_1:
key  col1 col2
---  ---- ----
1    abc  123
2    xyz  987

tbl_2:
key  col3 col4
---  ---- ----
1    bcd  12.5
2    zzz  11.1

tbl_3:
key  col1 col2 col3 col4
---  ---- ---- ---- ----
1    abc  123  bcd  12.5
2    xyz  987  zzz  11.1
[download]

Inspired by your bcp advice, I am just thinking whether I can bcp out tbl_1 and tbl_2, and then process the two bcp files to construct the bcp file for tbl_3. It should be much faster then inserting the sql statements.