在进行MERGE操作的时候，如何取得更新的行数和插入的行数？
 
首先创建测试表如下：
CREATE TABLE emp_source AS 
SELECT * FROM emp;       -- 14 rows
 
CREATE TABLE emp_target AS 
SELECT * FROM emp_source WHERE ROWNUM     -- 8 rows
 
创建用于获取插入行数的包：
CREATE OR REPLACE PACKAGE merge_demo AS
  FUNCTION merge_counter RETURN PLS_INTEGER;
  FUNCTION get_merge_insert_count RETURN PLS_INTEGER;
  PROCEDURE reset_counters;
END merge_demo;
/
 
CREATE OR REPLACE PACKAGE BODY merge_demo AS
  g_insert_counter PLS_INTEGER NOT NULL := 0;
 
  FUNCTION merge_counter RETURN PLS_INTEGER IS
  BEGIN
        g_insert_counter := g_insert_counter + 1;--注意：此函数永远返回0，即此函数不影--响插入，但在每次插入都进行计数。此是关键。
        RETURN 0;
  END merge_counter;
 
  FUNCTION get_merge_insert_count RETURN PLS_INTEGER IS
  BEGIN
        RETURN g_insert_counter;
  END get_merge_insert_count;
 
  PROCEDURE reset_counters IS
  BEGIN
        g_insert_counter := 0;
  END reset_counters;
 
END merge_demo;
/
 
以下代码通过上述包获取插入行数，并结合使用SQL%ROWCOUNT取得更新行数：
BEGIN
     MERGE INTO emp_target et
        USING ( SELECT * FROM emp_source ) es
        ON   ( et.empno = es.empno )
     WHEN MATCHED THEN
          UPDATE
          SET et.ename = es.ename, et.sal = es.sal, et.mgr = es.mgr, et.deptno = es.deptno
     WHEN NOT MATCHED THEN
          INSERT  ( et.empno, et.ename, et.sal, et.mgr, et.deptno)
          VALUES ( CASE merge_demo.merge_counter
                              WHEN 0 THEN es.empno
                         END
                       , es.ename, es.sal, es.mgr, es.deptno
                       );
     DBMS_OUTPUT.PUT_LINE( 'Total ' || SQL%ROWCOUNT || ' rows merged.' );
     DBMS_OUTPUT.PUT_LINE(merge_demo.get_merge_insert_count || ' rows inserted.');
     DBMS_OUTPUT.PUT_LINE( SQL%ROWCOUNT - merge_demo.get_merge_insert_count || ' rows updated.');
     merge_demo.reset_counters;
END;