(Oracle DB) - 15. SELECT

/* SELECT */
SELECT
	employee_id,
	emp_name
	FROM employees
WHERE salary > 5000
;

/* SELECT with ORDER BY */
SELECT
	employee_id,
	emp_name
	FROM employees
WHERE salary > 5000
ORDER BY employee_id
;

/* SELECT with AND */
SELECT
	employee_id,
	emp_name
	FROM employees
WHERE salary > 5000
AND job_id = 'IT_PROG'
ORDER BY employee_id
;

SELECT
	employee_id,
	emp_name
	FROM employees
WHERE salary > 5000
AND job_id = 'it_prog'	-- ERROR : 'IT_PROG' is upper case
ORDER BY employee_id
;

/* SELECT with OR */
SELECT
	employee_id,
	emp_name
	FROM employees
WHERE salary > 5000
OR job_id = 'IT_PROG'
ORDER BY employee_id
;

/* Alias to Table and Use 1 */
SELECT
	a.employee_id,
	a.emp_name,
	a.department_id,
	b.department_name
FROM
	employees a,
	departments b
WHERE a.department_id = b.department_id
;

/* Alias to Table and Use 2 */
SELECT
	a.employee_id,
	a.emp_name,
	a.department_id,
	b.department_name
		AS dep_name
FROM
	employees a,
	departments b
WHERE a.department_id = b.department_id
;