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For instance, there exists table A and table B, and i need to process an update in A and then B and I decide to table lock both them during use (as demanded by my architect). Simultaneously, another procedure is called which table locks B, then locks A.
Will this transaction complete? I have a feeling its a deadlock, quite sure of it as it’s not releasing any resources…
Yes it is a possible deadlock.
The deadlock scenario is
Your task locks A
Other task locks B
then
Your task tries to lock B but it can’t as you have the lock
and
other task tries to lock A but it can’t as you have it.
So one of these tasks has to fail/rollback so the other can complete. Depending on RDBMS used the db will choose one of these to terminate.
Often the solution is for a guideline that you must lock resources in the same order in all processes usually this has to be manualy enforced.