OCP 17 Exam - chapter 15 notes - JDBC

• Java provides JDBC interfaces, while database libraries provides implementations - except implementation of DriverManager, which is used to create connection (Q.1)
• if autocommit is enabled (default), then commit happens after every statement (Q.6)
• if nothing to rollback (changes has been commited), then rollback doesn’t throw any Exception (Q.6)
• rollback will throw if you try to rollback to already rollbacked savepoint (after savepoint used to rollback), so order matters. Also you cannot rollback to the same savepoint twice (Q.15)
• CallableStatement requires {} for every statement, e.g. {?= call my_databse_function(?) }
• CallableStatements OUT param should be registered, e.g. registerOutParameter(1, Types.INTEGER) (Q.14)
• be aware that JDBC code might throw SqlException, which is checked, so if not declared is compilation error (Q.10)
• be aware of missing ResultSet#next (moves query cursor), which might throw SqlException (Q.18)
• be aware of missing parameter - prepareStatement() requires SQL (Q.20)

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Credit: OCP Oracle Certified Professional Java SE 17 Developer Study Guide