1.查詢語句
select *from emp;
select *from dept;
select * from salgrade;
select ename ,sal *12 from emp;/*年薪*/
select 2*3 from emp;/*計算表示式*/
select ename ,sal*12 as "anuual sal" from emp;/* ""保持大小寫，年薪*/
select 2*3 from dual;/*用於計算*/
select ename || sal from emp;/*字串連線||*/
select distinct deptno from emp ;/*消除重複行*/
select distinct deptno ,job from emp;
select *from emp where deptno = 10;
select *from emp where ename = 'clerk';
select *from emp where deptno <> 10;
select ename , sal from emp where sal between 800 and 1500;
select ename , sal from emp where sal >-800 and sal <= 1500;
select ename , sal, comm from emp where comm is null;
select ename , sal, comm from emp where comm is not null;
select ename , sal, comm from emp where ename in ('king', 'smith','abc');
select ename , sal, hiredate from emp where hiredate > '20-2-1981';
select ename from emp where ename like '_a%';
select ename from emp where ename like '%$%%' escape '$';
select *from dept order by deptno desc;
select empno, ename from emp order by empno desc;
select ename ,sal*12 annual_sal from emp
where ename not like '_a%' and sal > 800
order by sal desc;
select lower(ename) from emp ;
select upper(ename) from emp ;
select ename from emp where lower(ename) like 'a%';
select substr(ename,2,3) from emp ; /*從第二個函式開始寫3個*/
/*其他函式省略*/
select to_char(sal ,'l00000.00') from emp;/*字元轉換*/
select to_char(hiredate ,'yyyy-mm-dd hh:mi:ss') from emp;/*字元轉換*/
select to_char(sysdate ,'yyyy-mm-dd hh24:mi:ss') from dual;/*字元轉換*/
select ename ,hiredate from emp where hiredate > to_char('2000-12-7','yyyy-mm-dd');
select count (ename)from emp;
select count (distinct deptno) from dept;
2.dml語句（資料操作語言）
insert into salgrade values (1,700,1200);
insert into salgrade values (2,1201,1400);
insert into salgrade values (3,1401,2000);
insert into salgrade values (4,2001,3000);
insert into salgrade values (5,3001,9999);
insert into dept values (10,'accounting','new york');
insert into dept values (20,'research','dallas');
insert into dept values (30,'sales','chicago');
insert into dept values (40,'opeartions','hoston');
insert into emp values (7369,'smith','clerk',7902,to_date( '17-12-80' , 'dd-mm-yy'),800, null ,20);
insert into emp values (7499,'allen','salesman',7698,to_date( '20-12 -81' ,'dd-mm-yy' ),1600, 300,30);
insert into emp values (7566,'jones','manager',7839,to_date( '02-4-81','dd-mm-yy'),2975,null ,20);
insert into emp values (7654,'martin','salesman',7698,to_date( '28-9-81' , 'dd-mm-yy' ),1250,1400,30);
insert into emp values (7566,'jones','manager',7839,to_date( '02-4-81' , 'dd-mm-yy'),2975, null ,20);
insert into emp values ( 7698 ,'blake','manager',7839,to_date( '01-5-81','dd-mm-yy' ),2850,null,30);
insert into emp values ( 7702 ,'clerk','manager',7839,to_date( '09-6-81' ,'dd-mm-yy' ),2450, null ,10);
/*缺失值一定要用null代替，否則報錯*/
insert into emp values ( 7700 ,'scott','analyst',7566,to_date( '19-4-07' , 'dd-mm-yy'),3000,null ,20);
insert into emp values ( 7039,'king','president', null ,to_date( '17-11-01', 'dd-mm-yy'),5000, null ,10);
insert into emp values ( 7844 ,'turner','salesman', 7698,to_date( '08-9-81', 'dd-mm-yy'),1500,0 ,30);
insert into emp values ( 7876 ,'adoms','clerk',7788 ,to_date( '23-5-87', 'dd-mm-yy'),1100, null ,20);
insert into emp values ( 7900 ,'james','clerk',7698 ,to_date( '03-12-81', 'dd-mm-yy'),950, null,30);
insert into emp values ( 7902 ,'ford','analyst',7566 ,to_date( '03-12-81', 'dd-mm-yy'),3000, null ,20);
insert into emp values ( 7934 ,'miller','clerk', 7782,to_date('23-1-82', 'dd-mm-yy'),1300,null ,10);
3.ddl語句（資料定義語言）
create table emp(
empno number(4) not null,
ename varchar(10),
job varchar(9),
mgr number(4),
hiredate date,
sal number(7,2),
comm number(7,2),
deptno number(2))
create table dept(deptno number(2) not null, dname varchar(14),
loc varchar(13))
create table salgrade(cgrade number,losal number,hisal number )
4.事務控制語句
delete from emp where ename= 'smith'
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