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Showing posts from December, 2018

PL/SQL 101: Defining and managing transactions

If you've got a read-only database, you don't have to worry about transactions. But for almost every application you're ever going to build, that is not the case. Therefore, the concept and managing of transactions is central to the success of your application. A transaction is a sequence of one or more SQL statements that Oracle Database treats as a unit: either all of the statements are performed, or none of them are. A transaction implicitly begins with any operation that obtains a TX lock: When a statement that modifies data is issued (e.g., insert, update, delete, merge) When a SELECT ... FOR UPDATE statement is issued When a transaction is explicitly started with a SET TRANSACTION statement or the DBMS_TRANSACTION package Issuing either a COMMIT or ROLLBACK statement explicitly ends the current transaction. This post reviews how to define, manage and control the transactions in your application with the following statements and features: Commit and Roll