Concurrency relate issue.

[Bhavin Patel]

I have one table that have 1000 record(for example).
there 2 user.

If 1st user select 100 record and then 2nd user tryies to select
records from that table records selected by 1st user is not shown to
2nd user. if 2nd tries to select all records then only 900 records
should be selected in these case.

1st 100 selected records should be available to public after
completion of operation.

Can anybody suggest me solution i am using postgresql 7.3

Thanks for spending your valueable time.
Bhavin Patel