MySQL 数据库

-- 插入完整记录 INSERT INTO students (name, age, gender, email) VALUES ('张三', 20, '男', 'zhangsan@example.com'); -- 插入多条记录 INSERT INTO students (name, age, gender, email) VALUES ('李四', 22, '女', 'lisi@example.com'), ('王五', 21, '男', 'wangwu@example.com'), ('赵六', 19, '女', 'zhaoliu@example.com'); -- 插入默认值 INSERT INTO students (name) VALUES ('钱七'); -- age将使用默认值（如果有设置），enrollment_date使用当前日期

-- 更新单个字段 UPDATE students SET age = 23 WHERE name = '张三'; -- 更新多个字段 UPDATE students SET age = 24, email = 'newemail@example.com' WHERE id = 1; -- 使用表达式更新 UPDATE students SET age = age + 1 WHERE gender = '男'; -- 更新所有记录（谨慎使用） -- UPDATE students SET status = 'active';

-- 删除特定记录 DELETE FROM students WHERE id = 5; -- 删除所有女生记录 DELETE FROM students WHERE gender = '女'; -- 删除所有记录（清空表） -- DELETE FROM students; -- 更快清空表（不可回滚） -- TRUNCATE TABLE students;

-- 比较操作符 =, <>, !=, >, <, >=, <=, -- BETWEEN范围查询 SELECT * FROM students WHERE age BETWEEN 18 AND 22; -- IN列表查询 SELECT * FROM students WHERE name IN ('张三', '李四', '王五'); -- LIKE模糊查询 SELECT * FROM students WHERE name LIKE '张%'; SELECT * FROM students WHERE email LIKE '%@gmail.com'; SELECT * FROM students WHERE name LIKE '_三'; -- IS NULL空值查询 SELECT * FROM students WHERE email IS NULL; -- 逻辑操作符 SELECT * FROM students WHERE age > 18 AND gender = '男'; SELECT * FROM students WHERE age < 20 OR gender = '女'; SELECT * FROM students WHERE NOT (age = 20);