On Tue, 11 May 2010 09:45:12 -0700 (PDT), Sandroid
wrote:


I don't want to delete IP address from tblIP, can I make tblIP lookup
table then? how to make make sure that each ip address is used only
once?
tblIP structu ID(primary),ip, ip2, ip3, ip4.

Lookup tables do more harm than good!

You can create a unique Index on the combination of the four ip fields; open
the table in design view, select the Indexes tool (like lightning hitting a
table), and type UniqueIP in the left column, and select IP in the right
column. On the next three rows put IP2, IP3 and IP4 in the right column under
IP. Check the Unique checkbox and it won't let you enter a duplicate IP.
--

John W. Vinson [MVP]