[3주차 3일] SQL 4 - DQL

DQL(Data Query Language)

: 데이터의 조회를 수행하는 SQL
SELECT

SELECT

: 데이터를 조회하는 SQL

- 형식
   select 컬럼명, 컬럼명, ....
   from 테이블명
   where 컬럼명 연산자 값 and/or 컬럼명 연산자 값 ....

ex>
select MNAME, PHONE
from MEMBERS
where MNAME = '임꺽정' and PHONE = '111-1112';
select * 
from MEMBERS
where MNAME = '임꺽정' and PHONE = '111-1112';

기본 연산자

: <, >, <=, >=, <>

ex>
select *
from MEMBERS
where 
REG_DATE >= '2013-08-12' and REG_DATE < '2013-08-15';

like 연산자

 - %: 0자 이상
 - _: 1자

ex>
select *
from MEMBERS
where MNAME like '임%'
;
select *
from MEMBERS
where MNAME like '%꺽정'
;
select *
from MEMBERS
where MNAME like '%꺽%'
;
select *
from MEMBERS
where MNAME like '임_정'
;
select *
from MEMBERS
where MNAME like '임__'
;
select *
from MEMBERS
where MNAME like '임_'
;

between 연산자 a and b

: x >= a and x <= b 와 같다

- 형식
between 값a and 값b

ex>
select *
from MEMBERS
where AGE >= 20 and AGE <= 30
;
select *
from MEMBERS
where AGE between 20 and 30
;

in 연산자

- 형식
in (값, 값, 값, ...)
ex>
select *
from MEMBERS
where AGE in (20, 30, 40)
;
select *
from MEMBERS
where AGE not in (30)
;

not에 대해서

ex>
select *
from MEMBERS
where not MNAME = '임꺽정'
;
select *
from MEMBERS
where MNAME <> '임꺽정'
;
select *
from MEMBERS
where MNAME != '임꺽정'
;

select *
from MEMBERS
where EMAIL = 'leem@test.com'
;