数据库对象更新维护示例

DECLARE
  BERSQL  VARCHAR2(100) := 'ALTER TABLE NSBRANCH RENAME TO NSBRANCH_BACK'; /*创建建视图前转储当前表*/
  DBLINK  VARCHAR2(40) := 'SMS_DBLINK'; /*DBLINK的名称*/
  VIEWSQL VARCHAR2(400) := 'CREATE OR REPLACE VIEW NSBRANCH AS SELECT A.BRANCH_NO AS BRNO,A.BRANCH_NAME AS BRNAME,A.BRANCH_TYPE AS ISCENTER,NULL AS CTACNTNO,NULL AS BANKACNTNO,NULL AS OPENBANK,NULL AS ADDRESS FROM CPM_BRANCH@SMS_DBLINK A'; /*创建视图*/
  TMP_STR VARCHAR2(80) := NULL; /*视图名称_NSBRANCH*/
BEGIN
  SELECT A.DB_LINK INTO TMP_STR FROM USER_DB_LINKS A WHERE A.DB_LINK = DBLINK;
  /*如果没有所需要的DB_LINK就抛异常*/
  IF TMP_STR IS NULL THEN
    RAISE_APPLICATION_ERROR(-20000,
                            '执行此语句所需要的DBLINK未创建或未正常工作请检查,DBLINK名称[' ||
                            DBLINK || ']');
  END IF;
  TMP_STR := NULL;
  SELECT A.OBJECT_NAME INTO TMP_STR FROM USER_OBJECTS A 
	WHERE A.OBJECT_NAME = 'NSBRANCH'AND A.OBJECT_TYPE = 'TABLE';
  /**如果表存在就转储此表,然后创建视图*/
  IF TMP_STR IS NOT NULL THEN
    EXECUTE IMMEDIATE BERSQL;
  END IF;
  EXECUTE IMMEDIATE VIEWSQL;
EXCEPTION
  WHEN OTHERS THEN
    DBMS_OUTPUT.PUT_LINE(SQLERRM);
END;