简单例子:管理员登录Oracle
select sid, username, decode(command, 0, 'None', 2, 'Insert', 3, 'Select', 6, 'Update', 7, 'Delete', 8, 'Drop', 'Other') command from v$session where username is not null;
语法结构:
decode(expression,search_1,result_1);
decode(expression,search_1,result_1,search_2,result_2);
decode(expression,search_1,result_1,search_2,result_2,… … search_n,result_n);
decode(expression,search_1,result_1,default);
decode(expression,search_1,result_1,search_2,result_2,default);
decode(expression,search_1,result_1,search_2,result_2,… … search_n,result_n,default);
decode(条件,值1,翻译值1,值2,翻译值2,… …值n,翻译值n);
decode(条件,值1,翻译值1,值2,翻译值2,… …值n,翻译值n,缺省值);