NVL 函數(shù)是 SQL 中的一個(gè)內(nèi)置函數(shù),它用于在查詢中處理 NULL 值
SELECT employee_id, employee_name, NVL(phone_number, 'Not available') AS phone_number
FROM employees;
SELECT employee_id, employee_name, department_id
FROM employees
WHERE NVL(department_id, -1) = -1;
SELECT department_id, AVG(NVL(salary, 0)) AS average_salary
FROM employees
GROUP BY department_id;
SELECT e.employee_id, e.employee_name, NVL(d.department_name, 'Unassigned') AS department_name
FROM employees e
LEFT JOIN departments d ON e.department_id = d.department_id;
SELECT employee_id, employee_name, salary, position,
NVL(salary, 0) * CASE position
WHEN 'Manager' THEN 0.1
WHEN 'Senior Developer' THEN 0.08
ELSE 0.05
END AS bonus
FROM employees;
總之,NVL 函數(shù)在 SQL 查詢中的深入應(yīng)用可以幫助你更好地處理 NULL 值,從而簡化查詢邏輯并提高查詢效率。在實(shí)際應(yīng)用中,你可以根據(jù)需求靈活地使用 NVL 函數(shù)來解決各種問題。