一 truncate语句

      Oracle中：truncate table table_name

      DB2中： truncate table table_name  immediate

二 取日期

      Oracle中 ：select to_char(sysdate,'yyyy-mm-dd') from dual

       DB2中   ： select current date from sysibm.sysdummy1

                           select current timestamp from sysibm.sysdummy1

 三 字符串截取

  Oracle ：  select substr('northqueen',1,2) from dual;

   DB2中：select left('northqueen,2'),right('suning',2) from sysibm.sysdummy1

四 类型转换

     Oracle中 ：select to_char(123) from dual

                         select to_number('123') from dual

     DB2中 ：select varchar(123)  from sysibm.sysdummy1

                       select char(123)  from sysibm.sysdummy1

                       select decimal('123') from sysibm.sysdumy1

  待续...