Using Transactions in Oracle

SELECT executed during the first command T1 is a transaction, in turn, DELETE comma开发者_运维知识库nd (at the time T2) is the first command transaction B. What will be the result of the SELECT statement at the time of T3 (a transaction)?

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The SELECT statement in T3 will return a row (because Transaction B is not committed yet) ?

Yes, it will, as the other transaction is not commited yet.

If you would try to do the same DELETE in Transaction A after the DELETE in Transaction B, then you would have to wait for the lock to be released, but a SELECT will work fine.