Record Locking

Hi There: I have two clients in their transactions as below. Client1----> begin work fetch a record R1 ..... update R1 commit work Client2-----> begin work fetch a record R1 update R1 commit Work Both the clients fetched the same record but client2 updated R1 before client1 did, so this resulted in client1's R1 to be an old copy. Is there a way I could lock a record to read in a transaction? Or is this kind of problem accepatable in Relational world as R1 is a copy and doesn't guarentee its state in d/b? Thanks in advance for ur answers. suresh