Basic questions on row locks

Question

Oracle 11.0.1.7
I just have a basic question about locks. What happens when 2 transactions at the same time try to delete the row? Does one get the row and other wouldn't? Is there a implicit locks that oracle takes care of?
Could you also point me to some examples or source.

Answer 1

That is what I have seen with for update and thought for update is for. But when I look at the oracle docs this is what it says. And what's confusing is "Permitted Operations" piece. It says other transactions can query, update etc.
A row exclusive table lock (also called a subexclusive table lock, SX) generally indicates that the transaction holding the lock has made one or more updates to rows in the table or issued SELECT ... FOR UPDATE. A row exclusive table lock is acquired automatically for a table modified by the following types of statements:
SELECT ... FROM table ... FOR UPDATE OF ...;
INSERT INTO table ... ;
UPDATE table ... ;
DELETE FROM table ... ; 
LOCK TABLE table IN ROW EXCLUSIVE MODE;
A row exclusive table lock is slightly more restrictive than a row share table lock.
Permitted Operations: A row exclusive table lock held by a transaction allows other transactions to query, insert, update, delete, or lock rows concurrently in the same table. Therefore, row exclusive table locks allow multiple transactions to obtain simultaneous row exclusive and row share table locks for the same table.
Prohibited Operations: A row exclusive table lock held by a transaction prevents other transactions from manually locking the table for exclusive reading or writing. Therefore, other transactions cannot concurrently lock the table using the following statements:
LOCK TABLE table IN SHARE MODE; 
LOCK TABLE table IN SHARE ROW EXCLUSIVE MODE;
LOCK TABLE table IN EXCLUSIVE MODE;