Примеры команд SQL в рамках урока #8

-- Фильтрация строк в запросе Select. Специфика значений NULL
-- https://www.youtube.com/watch?v=5P0a5SODbEQ

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-- Примеры команд SQL в рамках урока #8


SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, MANAGER_ID, DEPARTMENT_ID
FROM employees
WHERE
     department_id = 90
;

SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, MANAGER_ID, DEPARTMENT_ID
FROM employees
WHERE
    department_id = 90
    AND manager_id = '(null)'
;

SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, MANAGER_ID, DEPARTMENT_ID
FROM employees
WHERE
    department_id = 90
    AND manager_id IS NULL
;

SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, MANAGER_ID, DEPARTMENT_ID
FROM employees
WHERE
    department_id = 90
    AND manager_id IS NOT NULL
;

SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, nvl(MANAGER_ID, 0) AS MANAGER_ID, DEPARTMENT_ID
FROM employees
WHERE
    department_id = 90
;