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show tables;
table 출력 -
desc employees;
테이블 구조 -
select * from employees limit 0, 10;
10개씩 조회 -
select first_name, last_name, salary from employees;
first_name, last_name, salary 컬럼만 조회 -
select first_name as 이름, hire_date as 입사일 from employees;
alias -
select concat(first_name, ' ', last_name) as 이름, hire_date as 입사일 from employees;
first_name, last_name을 공백 기준으로 합친다. -
select distinct manager_id from employees;
중복 제거 -
select first_name, last_name, hire_date, salary from employees order by salary desc;
오름차순 정렬 -
select * from employees where last_name = "king";
last name이 'king'인 사람을 조회 -
select * from employees where hire_date > '1998-02-05' order by hire_date;
hire_date > 1998-02-05인 사람만 조회하고 정렬 -
select * from employees where first_name = 'steven' and last_name = 'king';
first_name과 last_name이 일치하는 사람을 조회 -
select * from employees where first_name = 'steven' or last_name = 'king';
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select * from employees where commission_pct is null;
commission_pct 컬럼 값이 null인 경우만 조회 -
select * from employees where first_name like '%t';
패턴 매칭 -
select * from employees where first_name like 'H____';
패턴 매칭 -
select * from employees where department_id = 90 or department_id = 100;
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select * from employees where department_id in(90, 100);
위 쿼리와 똑같은 결과를 조회 -
select ucase(last_name) from employees;
대문자로 변경해 조회 -
select upper(last_name) from employees;
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select lcase(last_name) from employees;
소문자로 변경해 조회 -
select substring('happy day', 4,2);
4인덱스부터 문자열 2개 조회 -
select substring(first_name, 1, 1) from employees;
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select * from employees where substring(first_name, 1, 1) = 'A';
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select * from employees where first_name like 'A%';
substring보다like사용을 추천한다.
