在SQL中，NOT(IS NULL)与is NOT NULL有什么不同？

-- 检查字段是否不为NULL
SELECT * FROM table_name WHERE column_name IS NOT NULL;

-- 等价的写法
SELECT * FROM table_name WHERE NOT (column_name IS NULL);

-- 查找所有不为NULL的记录
SELECT * FROM users WHERE email IS NOT NULL;

-- 等价的写法
SELECT * FROM users WHERE NOT (email IS NULL);

-- 创建一个示例表
CREATE TABLE users (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(100)
);

-- 插入一些数据
INSERT INTO users (id, name, email) VALUES
(1, 'Alice', 'alice@example.com'),
(2, 'Bob', NULL),
(3, 'Charlie', 'charlie@example.com');

-- 查询不为NULL的email
SELECT * FROM users WHERE email IS NOT NULL;

-- 等价的查询
SELECT * FROM users WHERE NOT (email IS NULL);