Oracle PL/SQL之EXCEPTION -- WHEN OTHERS THEN

　　在处理EXCEPTION时应特别注意WHEN OTHERS THEN的使用，因为WHEN OTHERS THEN会吃掉所有的EXCEPTION。如果在WHEN OTHERS THEN后不抛出任何信息，即：WHEN OTHERS THEN NULL; 这可能会极大地增加以后程序排错的难度，因为即使出错了，也没有任何提示。所以我们需要特别留意WHEN OTHERS THEN，除了一个一个的手工查找外，还可以采用如下命令以便在编译时就进行检查：
　　ALTER SESSION SET plsql_warnings = 'enable:all';
　　
　　测试样例：
　　Connected to Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 Connected as xxpoSQL> set serveroutput onSQL> ALTER SESSION SET plsql_warnings = 'enable:all';Session alteredSQL> @"D:/test/xxpotest.plb";Package body createdSQL> sho err;Errors for PACKAGE BODY XXPO.XXPO_TEST_PKG:LINE/COL ERROR-------- --------------------------------------------------------------------------------------------------88/13    PLW-05004: identifier LOG is also declared in STANDARD or is a SQL builtin285/5    PLW-07203: parameter 'X_MESSAGE' may benefit from use of the NOCOPY compiler hint504/5    PLW-07203: parameter 'X_MESSAGE' may benefit from use of the NOCOPY compiler hint569/5    PLW-07203: parameter 'X_MESSAGE' may benefit from use of the NOCOPY compiler hint1008/14  PLW-07204: conversion away from column type may result in sub-optimal query plan1027/14  PLW-07204: conversion away from column type may result in sub-optimal query plan2027/12  PLW-07204: conversion away from column type may result in sub-optimal query plan1667/14  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1716/14  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1773/14  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1755/14  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1737/14  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1789/10  PLW-06009: procedure "SET_STG_TBL" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR2046/10  PLW-06009: procedure "MAIN" OTHERS handler does not end in RAISE or RAISE_APPLICATION_ERROR1910/11  PLW-06002: Unreachable codeSQL>