Oacle 학습 노트 (2) 표 조회

  1 --oracle    

  2 

  3 --   

  4 create table users(userName varchar2(20));

  5 --   

  6 drop table users;

  7 --   

  8 create table student(xh number(4),xm varchar2(20),sex char(2),birthday date,sal number(7,2));

  9 create table classes(classId number(2),cnmae varchar2(40));

 10 --      

 11 alter table  student add (classId number(2));

 12 --      

 13 alter table student modify(xm varchar2(30));

 14 --      /    （     ）

 15 alter table student modify(xm char(30));

 16 --            

 17 alter table student drop column sal;

 18 --      

 19 rename student to stu;

 20 --   

 21 drop table student;

 22 --oracle        'DD-MON-YY' DD   ，MON    YY   

 23 --                

 24 alter session set nls_date_format='DD-MM-YYYY'

 25 --    

 26 insert into student(xh,xm,sex,birthday) values(1,'aa',' '，null);

 27 --       

 28 select * from student where birthday is null;

 29 --      

 30 select * from student where birthday is not null;

 31 --                 

 32 update student set sal=sal/2 where sex=' ';

 33 --    

 34 --       ，     ，   ,     ，   

 35 delect from student;

 36 --         

 37 drop table student;

 38 --         ，     ，    ，         ，   

 39 truncate table student;

 40 --     

 41 savepoint a;

 42 --   a 

 43 rollback to a;

 44 --///////////////////////////////

 45 commit

 46 --    

 47 --     

 48 sesc dept;

 49 select * from emp;

 50 select * from dept;

 51 --    

 52 create table users(userId varchar2(20),userName varchar2(20),userpasswd varchar2(20));

 53 insert into users values('001','aaa','12aaa');

 54 insert into users(userId,userName,userpasswd) select * from users;

 55 --      distinct

 56 select distinct  deptno,job from emp;

 57 --  SMITH   deptno，job，sal  

 58 select deptno,job,sal from emp where ename='SMITH'

 59 --       

 60 --          

 61 select ename,sal*13 "   " from emp; 

 62 --     

 63 --  null    nvl       

 64 --     comm        0  ，      comm 

 65 select ename,sal*13+nvl(comm,0)*13 "   " from emp;

 66 --      3000   

 67 select * from emp where sal>3000;

 68 --  1982 1.1      

 69 select ename,hiredate from emp where hiredate>'1-1-1982';

 70 --     2000 2500   

 71 select * from emp where sal>2000 and sal<2500;

 72 --like    

 73 --%     0     

 74 -- _        

 75 --              

 76 select ename ,sal from emp where ename like 'S%'

 77 --          O     

 78 select ename ,sal from emp where ename like '__O%'

 79 --  in

 80 select * from emp where  empno in (7844,234,345);

 81 --        

 82 select * from emp where mgr is null;

 83 

 84 --      

 85 select * from emp where (sal>500 or job='MANAGER') and ename like 'J%'

 86 --       

 87 select * from emp  order by sal;

 88 --      

 89 select * from emp order by sal desc;

 90 --          ，         （  ）

 91 select * from emp order by deptno ,sal desc;

 92 --       ，      

 93 select * from emp order by deptno,hiredate ;

 94 --                 

 95 select ename,sal*12+nvl(comm,0)*12 "  " from emp order by "  ";

 96 ---////////////////////////

 97 --      

 98 --                

 99 --            

100 select  max(sal),min(sal) from emp;

101 --          

102 select ename,sal from emp where sal =(select max(sal) ab from emp);

103 --             

104 select * from emp where sal<( select avg(sal) from emp);

105 --group by   

106 --having   

107 --                

108 select avg(sal),max(sal),min(sal),deptno ,job from emp group by deptno,job;

109 --        2000           

110 select avg(sal),max(sal),deptno from emp group by deptno having avg(sal)>2000;

111 --  

112 --             ，having,order by   

113 -- select      group by>having>order by

114 select avg(sal),max(sal),deptno from emp group by deptno having avg(sal)>2000 order by avg(sal) desc;

115 --//////////////////////////////////

116 --     

117 --     ，    ，       ,   emp  dept 

118 select ab.ename ,ab.sal ,ac.dname from emp ab,dept ac where ab.deptno=ac.deptno

119 --        10    ，      

120 select a1.ename,a2.dname,a1.sal from emp a1,dept a2 where a1.deptno=a2.deptno and a1.deptno=10

121 --     ，    ，        ，       

122 select a1.ename,a1.sal,a2.dname from emp a1,dept a2 where a1.deptno=a2.deptno order by a1.deptno;

123 --   

124 --          'FORD'

125 select worker.ename "  ",boss.ename "  " from emp worker ,emp boss where worker.mgr=boss.empno and worker.ename='FORD';

126 --   

127 --     

128 ---   smith   ，         

129 select * from emp where (deptno,job)=(select deptno,job from emp where ename='SMITH')

130 --                    

131 --1.         

132 select avg(sal) mysal ,deptno from emp group by deptno

133 --2.             

134 select * from emp a2,(select avg(sal) mysal ,deptno from emp group by deptno) a1 where a2.deptno=a1.deptno and a2.sal>a1.mysal;

135 ---////////////////////////////////////////

136 --oracle  ，     

137 --1.rownum  

138 select * from emp;

139 --2.  rownum

140 select a1.* ,rownum rn from (select * from emp) a1 ;

141 --3.   

142 --a,     ，        

143 --b,  ,           

144 select a2.* from (select a1.* ,rownum rn from (select ename,sal from emp order by sal) a1 where rownum<9)a2 where rn>=6;

145 --/////////////////////

146 --           

147 create table myemp2(id,ename,sal)as select empno,ename,sal from emp;

148 desc myemp2;

149 select * from myemp2;

150 --    

151 --      select     ，           union ,union all,minus,intersect

152 --union                  ，                       

153 --union       union  ，        ，      

154 --minus       ，            ，           ，