SQL 增删改查-简单应用-熟悉掌握
– 查询用户表中所有的数据 – SELECT * FROM users;
– 只查询用户的用户名和密码 – SELECT username,password FROM users;
– 添加 – INSERT INTO users (username,password) VALUES(‘moana’,‘1234’); – SELECT * FROM users;
– 更新 – UPDATE users SET password=12345,status=1 WHERE id=3;
– 删除 – DELETE FROM users WHERE id=4
– 筛选出id不等3的列表项 – SELECT * FROM users WHERE id<>3;
– SELECT *FROM users WHERE id=1 AND status=0; – SELECT * FROM users WHERE username=‘zjm’ OR status=1
– 降序 – SELECT * FROM users ORDER BY id DESC – 升序(如果密码有同样的,可以再按照id 的降序排序) – SELECT * FROM users ORDER BY password,id DESC;
– 统计符合筛选条件的 数量 SELECT COUNT(*) AS total FROM users WHERE status=0;