4.MySQL表的增删改查（进阶）

增加记录：

INSERT INTO students (id, name, age) VALUES (1, '张三', 20);

删除记录：

DELETE FROM students WHERE id = 1;

更新记录：

UPDATE students SET age = 21 WHERE id = 1;

查询记录：

SELECT * FROM students WHERE age > 18;

批量更新：

UPDATE students SET age = age + 1 WHERE id IN (1, 2, 3);

复合查询（AND, OR, NOT, LIKE）：

SELECT * FROM students WHERE age > 18 AND gender = 'male';
SELECT * FROM students WHERE age < 20 OR age > 30;
SELECT * FROM students WHERE NOT name LIKE '张%';

排序和限制结果数量：

SELECT * FROM students ORDER BY age DESC LIMIT 5;

分组和聚合：

SELECT gender, COUNT(*) FROM students GROUP BY gender;

连接查询（JOIN）：

SELECT students.name, courses.name FROM students JOIN courses ON students.id = courses.student_id;

子查询：

SELECT name FROM students WHERE id IN (SELECT student_id FROM scores WHERE score > 80);

这些是MySQL表的增删改查操作的进阶用法，涵盖了常用的SQL操作。