데이터베이스에서는 '코드' 라 하지 않고 '쿼리' 라고 한다.
SELECT 속성 이름
FROM 테이블 이름
WHERE 검색 조건
AND 검색 조건
;
SELECT TNAME
FROM TAB;
-- 조회는 ctrl + enter
SELECT *
FROM EMPLOYEES
;
SELECT *
FROM EMPLOYEES
WHERE LAST_NAME = 'Austin'
;
SELECT *
FROM EMPLOYEES
WHERE EMPARTMENT_ID = 60
AND MANAGER_ID = 102
;
SELECT EMPLOYEE_ID, LAST_NAME
FROM EMPLOYEES
WHERE LAST_NAME = 'Smith'
;
SELECT *
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
AND JOB_ID = 'FI_MGR'
;
별칭 (AS, 알리아스)
SELECT EMPLOYEE_ID AS "ID", SALARY "SAL", DEPARTMENT_ID DE
-- AS 생략 가능
-- 쌍따옴표를 안해도 된다.
FROM EMPLOYEEES e
;
함수
SELECT DISTINCT JOB_ID
FROM EMPLOYEES e
;
비교
SELECT FIRST_NAME, LAST_NAME, SALARY
FROM EMPLOYEES e
WHERE SALARY >= 5000
;
---------------------------------------
SELECT *
FROM EMPLOYEES e
WHERE SALARY < 2500
;
---------------------------------------
-- salary 4000 ~ 8000, first_name, last_name, salary
SELECT FIRST_NAME , LAST_NAME , SALARY
FROM EMPLOYEES e
WHERE SALARY >= 4000
AND SALARY <= 8000
;
or
SELECT *
FROM EMPLOYEES e
WHERE DEPARTMENT_ID = 50
OR MANAGER_ID = 100
;
SELECT *
FROM EMPLOYEES e
WHERE NOT(DEPARTMENT_ID = 50)
;
SELECT *
FROM EMPLOYEES e
WHERE DEPARTMENT_ID <> 50
SELECT *
FROM EMPLOYEES e
WHERE DEPARTMENT_ID != 50
;
-> 전부다 EMPLOYEES 테이블에서 DEPARTMENT_ID 컬럼 값이 50이 아닌 것을 조회