SQL面试（SQL interview）.doc

SQL面试（SQL interview） You cannot use the ROLLBACK command for TRUNCATE. 3. TRUNCATE will reset the high horizontal and all indexes. When fully browsing the entire table and index, the table after TRUNCATE is much faster than the table after the DELETE operation. 4. TRUNCATE cannot trigger any DELETE trigger. 5. No person should be granted permission to empty the other persons table. 6. When the table is cleared, the index of the table and table is reset to the initial size, while delete cannot. 7. Unable to clear the parent table. Tell me about your understanding of the business. ORACLE transactions from COMMIT, ROLLBACK, connection to the database, or start first The execution of an executable SQL statement starts with a COMMIT, a ROLLBACK statement, or exit The database ends. If a DDL statement is included in a transaction, it is in the DDL statement A COMMIT statement is implicitly executed before and after, and a transaction begins or ends. If a transaction is due to some failure or a user changes an idea, it must be Before it is submitted, the database is restored to these statements and the process before execution State. Using the ROLLBACK statement can be undone or returned at any time before the COMMIT command The transaction. You can return the entire transaction, or you can return some of the transactions, but you cant go back An already committed transaction. The ROLLBACK command for the back part of the transaction is: ROLLBACK to savepoint storage roll call The storage point is a token that the user puts in a transaction to indicate a return Position. The storage point is inserted by placing a SAVEPOINT command in the transaction. the The syntax of the command is: SAVEPOINT storage roll call If there is no storage roll call in the ROLLBACK statement, the entire transaction is returned To go back. 12. How to add A list of ABC to table A? The database should be in a state of silence when the database is being applied Alter table a add ABC varchar2 (10), I