FORALL与BULK COLLECT的使用方法:
1．使用FORALL比FOR效率高，因为前者只切换一次上下文，而后者将是在循环次数一样多个上下文间切换。

2．使用BLUK COLLECT一次取出一个数据集合，比用游标条取数据效率高，尤其是在网络不大好的情况下。但BLUK COLLECT需要大量内存。
create table test_forall ( user_id number(10), user_name varchar2(20));
select into 中使用bulk collect
DECLARE
  TYPE table_forall IS TABLE OF test_forall%ROWTYPE;
  v_table table_forall;
BEGIN
    SELECT mub.user_id,mub.user_name
         BULK COLLECT INTO v_table
    FROM mag_user_basic mub
         WHERE mub.user_id BETWEEN 10000 AND 10100;
    FORALL idx IN 1..v_table.COUNT
           INSERT INTO test_forall VALUES v_table(idx);
           --VALUES(v_table(idx).user_id,v_table(idx).user_name);Error
           --在PL/SQL中，BULK In-BIND与RECORD，%ROWTYPE是不能在一块使用的，
           --也就是说，BULK In-BIND只能与简单类型的数组一块使用
    COMMIT;
EXCEPTION
    WHEN OTHERS THEN
        ROLLBACK;

END;
fetch into 中使用bulk collect
DECLARE
  TYPE table_forall IS TABLE OF test_forall%ROWTYPE;
  v_table table_forall;

  CURSOR c1 IS
    SELECT mub.user_id,mub.user_name
         FROM mag_user_basic mub
           WHERE mub.user_id BETWEEN 10000 AND 10100;
BEGIN
   OPEN c1;
   --在fetch into中使用bulk collect
   FETCH c1 BULK COLLECT INTO v_table;

   FORALL idx IN 1..v_table.COUNT
         INSERT INTO test_forall VALUES v_table(idx);
    COMMIT;
EXCEPTION
    WHEN OTHERS THEN
        ROLLBACK;
END;
在returning into中使用bulk collect
CREATE TABLE test_forall2 AS SELECT * FROM test_forall;
----在returning into中使用bulk collect
DECLARE
   TYPE IdList IS TABLE OF test_forall.User_Id%TYPE;
   enums IdList;
   TYPE NameList IS TABLE OF test_forall.user_name%TYPE;
   names NameList;
BEGIN
   DELETE FROM test_forall2 WHERE user_id = 10100
        RETURNING user_id, user_name BULK COLLECT INTO enums, names;
   dbms_output.put_line('Deleted ' || SQL%ROWCOUNT || ' rows:');
   FOR i IN enums.FIRST .. enums.LAST
   LOOP
     dbms_output.put_line('User #' || enums(i) || ': ' || names(i));
   END LOOP;
   COMMIT;

EXCEPTION
    WHEN OTHERS THEN
        ROLLBACK;

END;
--批量更新中，将for改成forall
DECLARE
    TYPE NumList IS VARRAY(20) OF NUMBER;
    depts NumList := NumList(10, 30, 70, ...);
 -- department numbers
     BEGIN
   
       /*FOR i IN depts.FIRST..depts.LAST
       LOOP
       ...
       --UPDATE statement is sent to the SQL engine
       -- with each iteration of the FOR loop!
         UPDATE emp SET sal = sal * 1.10 WHERE deptno = depts(i);
       END LOOP:
      */
       FORALL i IN depts.FIRST..depts.LAST
        UPDATE emp SET sal = sal * 1.10 WHERE deptno = depts(i);
       commit;
    END;