Oracle row lock Select for update

Oracle row lock Select for update

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Statement: An SQL statement. Session: A connection generated by an Oracle user, a user can produce multiple sessions, but is independent of each other. Transaction: All the changes can be divided into transaction, a transaction contains one or more SQL. When a session is established, it is a time when a transaction begins, after which the transaction start and end are controlled by the DCL, which means that each commit/rollback is marked by the end of a transaction. Consistency: Is for the statement level, not the transaction level. The data obtained by SQL statement is an image that begins with SQL statement. Usage Description: UPDATE, INSERT, delete, select ... for update will lock the corresponding row. Only one transaction can lock the corresponding line, that is, if a row has been locked, it cannot be locked by the other transaction. Lock is generated by statement but ends with transaction (Commit,rollback), which means that the lock will exist after a SQL is completed, and only after the Commit/rollback is released.

Oracle row lock Select for update