There are 2 types of LOCK in dbms: table-locked and row-locked. maybe
you should consult the db2 documentation.
I don't think these 2 transcation can run concurrently. for example:
the table "table1" like this:
--------------------------
field1 field2
'aa' 12
'bb' 20
'cc' 30
--------------------------
update1 is "update table1 set field2=22 where field1='aa'"
update3 is "update table1 set field1='dd' where field2>=20"
the result of the these 2 transaction is not sure if they run concurrently.