문자 함수

• Oracle SQL Developer에서는 SQL Plus사용 X

LOWER : 소문자로 반환
INITCAP : 앞글자만 대문자로 반환

SELECT employee_id, first_name,
LOWER(job_id), INITCAP(job_id) 
FROM employees WHERE department_id=10;

CONCAT : 글자 병합(순서대로)

SELECT employee_id, first_name, job_id, 
CONCAT(employee_id, first_name) AS first_name, 
CONCAT(first_name, employee_id) e_employee_id, 
CONCAT(first_name, job_id) AS e_job
FROM employees
WHERE department_id=10; 

SUBSTR(문자열, 시작, 끝) : 문자열 중 지정한 위치에서 지정한 길이만큼의 문자열을 반환

SELECT employee_id, first_name, job_id, salary, department_id
FROM employees
WHERE SUBSTR(first_name,1,1) BETWEEN 'K' AND 'Y'
ORDER BY first_name;