Oracleѧϰ±Ê¼Çժ¼3

 ¡¶1¡·DDLÓï¾ä(Êý¾Ý¶¨ÒåÓïÑÔ) Data Define Language
   create
   alter
   drop
   truncate ¿ªÍ·µÄÓï¾ä truncate table <±íÃû>
      Ìصã:<1>½¨Á¢ºÍÐÞ¸ÄÊý¾Ý¶ÔÏó
           <2>½¨Á¢ºÍÐÞ¸ÄÖ±½Ó´æÈë¿âÖÐ,Ö±½ÓÉúЧ
    ½¨Á¢±í
       create table class(--°à¼¶±í
          classid number(2) primary key,
          cname varchar2(20) not null);
       /*wdsadsadsad
         asdsadsadsadsad
         ¶àÐÐ×¢ÊÍ  
        */  
       create table student( --ѧÉú±í
         xh number(4) primary key, --ѧºÅ
         name varchar2(10) not null, --ÐÕÃû
         sex  char(2)  check (sex in ('ÄÐ','Å®')),--ÐÔ±ð
         birthday date,--ÉúÈÕ
         sal number(7,2), --½±Ñ§½ð
         classid number(2) references class(classid) --°à¼¶          
       );
 Íâ¼üÒýÓõÄÁÐÒ»¶¨ÊÇÖ÷¼ü»òÓÐuniqueÔ¼ÊøµÄÁÐ
 
  alter table student add (shengfenzheng number(18));
  drop table student;  ɾ³ý½á¹¹
  delete from student; ֻɾ³ýÊý¾Ý£¬ËÙ¶ÈÂý£¬Êý¾Ý¿ÉÒÔ»Ö¸´
  truncate table student; ɾ³ý¼Ç¼µÄ Ëٶȿì Êý¾Ý²»Äָܻ´
 ¡¶2¡· DMLÓï¾ä(Êý¾Ý²Ù×÷ÓïÑÔ) Data Manupilate Language     
   select
   insert
   delete
   update