You receive complaints from users regarding the high waiting time for their transactions. Oninvestigation， you find that some users are not committing their transactions though they are 
notperforming any activity for a long time. As a result， SQL statements need to wait for row-level locks. 
Which two actions could you take to prevent this locking problem in the future（）

多项选择题WhichtwostatementsdescribegoodpracticesforanapplicationdevelopertoreducelockingconflictsinOracledatabase（）

A.Avoid coding unnecessary long-running transactions.
B.Allow the database to handle locks in default locking mode.
C.Always explicitly code the locks as per the requirement of the application.
D.Allow escalation of row locks to block locks if too many row locks cause problem.

单项选择题User A executes the following command to drop a large table in your database： SQL> DROP TABLE trans；  While the drop table operation is in progress， user B executes the following command on the same table： SQL> DELETE FROM trans WHERE tr_type=’SL’；  Which statement is true regarding the DELETE command（）

A.It fails with a "Resource Busy" error.
B.It deletes the rows successfully because the table is locked in SHARE mode.
C.It fails to delete the records because the table is locked in EXCLUSIVE mode.
D.It deletes the rows successfully because the table is locked in SHARE ROW EXCLUSIVE mode.

单项选择题You suspect unauthorized data manipulation language （DML） operations on a particular table. Youwant to track users who are performing the transactions and the values used in the transactions. You alsoplan to transfer these values to another table for analysis.  How would you achieve this（）

A.by using triggers
B.by using Data Pump
C.by using external tables
D.by using anonymous PL/SQL blocks

多项选择题User SCOTT executes the following command on the EMP table but has not issued COMMIT， ROLLBACK， or any data definition language （DDL） command： SQL> SELECT ename FROM emp  2 WHERE job=’CLERK’ FOR UPDATE OF empno；  SCOTT has opened another session to work with the database instance.  Which three operations wouldwait when issued in SCOTT’s second session（）

A.LOCK TABLE emp IN SHARE MODE；
B.LOCK TABLE emp IN EXCLUSIVE MODE；
C.UPDATE emp SET sal=sal*1.2 WHERE job=MANAGER；
D.INSERT INTO emp（empno，ename） VALUES （1289，’Harry’）；
E.SELECT ename FROM emp WHERE job=’CLERK’ FOR UPDATE OF empno；

单项选择题The HR user creates a stand-alone procedure as follows and grants the EXECUTE privilege on theprocedure to many database users：  CREATE OR REPLACE PROCEDURE create_dept （ v_deptno NUMBER， v_dname VARCHAR2， v_mgr NUMBER， v_loc NUMBER） BEGIN  INSERT INTO hr.departments VALUES （v_deptno， v_dname， v_mgr， v_loc）； END；  The users having permission to execute the procedure are able to insert records into the  DEPARTMENTStable even though they do not have the INSERT privilege on the table. You want only those users whohave privileges on the DEPARTMENTS table to be able to execute the procedure successfully.  What would you suggest to the PL SQL developers to achieve this（）

A.Create the procedure with definer’s right.
B.Create the procedure with invoker’s right.
C.Grant the EXECUTE privilege with GRANT OPTION on the procedure to selected users.
D.Create the procedure as part of a PL/SQL package and grant the EXECUTE privilege on the package to selected users