Where, 비교 연산자,

SELECT mem_uno
FROM billing
WHERE 구매횟수>=10;

TRUE=1
FALSE=0

비교연산자 : =,<,>
논리연산자 = NOT, AND OR
기타연산자 = BETWEEN

같지않다 !=, <>

 

USE pokemon;

SELECT number
FROM mypokemon
WHERE name='pikachu';

WHERE : 조건식이 TRUE가 되는 raw만 선택

SELECT name
FROM mypokemon
WHERE speed>50;

SELECT name
FROM mypokemon
WHERE type!='electric';

논리연산자, AND OR NOT

SELECT name
FROM mypokemon
WHERE speed<=100 AND type='electric';

SELECT name
FROM mypokemon
WHERE type IN ('bug', 'normal');

SELECT name
FROM mypokemon
WHERE type='bug' OR type='normal';

SELECT name
FROM mypokemon
WHERE speed<=100 AND NOT(type='bug');

Between 

SELECT name
FROM mypokemon
WHERE speed BETWEEN 50 AND 100;

IN 

목록에 넣을 값이 여러개일때 OR 보다 표현 이해가 쉬움
컬럼이름 IN (A, B) 는 컬럼=A OR 컬럼=B 동일

SELECT name
FROM mypokemon
WHERE type IN('bug', 'normal');

 

LIKE

문자열 연산자 LIKE
검색할 문자열 내 "와일드카드"를 사용하여 검색조건을 구체적으로 표현할 수있습니다

% :
_ : 1개
__: 2개

e로 끝나는 문자열
%e : e, ee, eevee, apple, pineapple

e로 시작하는 문자열
e% : e, ee, eevee, eric

e가 포함된 문자열
%e% : e, ee, eevee, apple, pineapple, aespa

e로 끝나고 e 앞에 1개의 문자가 있는 문자열
_e : ae, ee, ce

e로 끝나고 e앞에 1개 이상의 문자가 있는 문자열
%_e : ee, eevee, apple, pineapple

e를 포함하고, e 앞 뒤로 1개이상의 문자가 있는 문자열
%_e_% : eevee, aespa

USE pokemon;
SELECT name
FROM mypokemon
WHERE name LIKE '%chu';

SELECT name
FROM mypokemon
WHERE name LIKE '%a%';

 

IS NULL

IS NOT NULL