Oracleѧϰ±Ê¼Çժ¼1

 1.create alter insert update selectµÈ
ÈçºÎ½¨±í
   ѧÉú±ístudent
        create table student( --ѧÉú±í
           xh number(4), --ѧºÅ
           xm varchar2(10), --ÐÕÃû
           sex char(2), --ÐÔ±ð
           birthday date, --ÈÕÆÚ
           sal number(7,2) --½±Ñ§½ð
        );
   °à¼¶class
       create table class( --°à¼¶±í
          classid number(2), --°à¼¶±àºÅ
          cname varchar2(20) --°à¼¶Ãû×Ö
       );
  Ìí¼Ó×Ö¶Î(ѧÉúËùÔڰ༶classid)
      alter table student add (classid number(2));
  ÐÞ¸Ä×ֶεij¤¶È
      alter table student modify (xm varchar2(12)) ;
  ÐÞ¸Ä×ֶεÄÀàÐÍ(²»ÄÜÓмǼµÄ)
      alter table student modify (xh varchar2(5));
  ɾ³ýÒ»¸ö×Ö¶Î
      alter table student drop column sal;
  ɾ³ý±í
      drop table student;
  ±íµÄÃû×ÖÐÞ¸Ä
      rename student to stu;
  ×Ö¶ÎÈçºÎ¸ÄÃû×Ö
      --ÏÈɾ³ý
      a)alter table student drop column sal;        
      --ÔÙÌí¼Ó
      b)alter table student add (salary number(7,2));
ÈçºÎ²åÈëÊý¾Ý
  ²åÈëÊý¾Ý insertÓï¾ä
      ËùÓÐ×ֶζ¼²åÈë
       insert into student values ('A001','ÕÅÈý','ÄÐ','01-5ÔÂ-05',10);
 &n