简单的SQL语句学习

CREATE DATABASE db_test;
USE db_test;
CREATE TABLE USER(
    uid INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(30) NOT NULL,
    PASSWORD VARCHAR(30) NOT NULL,
    uname VARCHAR(10) NOT NULL,
    phone VARCHAR(11) UNIQUE 
     
)
/*
数据库增加
*/
INSERT INTO USER(uid,username,PASSWORD,uname,phone)
    VALUES(NULL,"马文飞","123456","马文飞","16637809505");
INSERT INTO USER(uid,username,PASSWORD,uname,phone)
    VALUES(NULL,"翟华兵","123456","翟华兵","16637809506");
    
/*
数据库更改
*/
UPDATE USER SET phone = "16637801234" WHERE uid = 2;
/*
数据库删除
*/
DELETE FROM USER; 
DELETE FROM USER WHERE uname = "马文飞"; 

#将这张表删除，再创建一个新表，是新的主键索引
TRUNCATE TABLE USER;

/*
查看数据库
*/    
SELECT uname,phone FROM USER;
SELECT uname,phone FROM USER WHERE uid = "1";
SELECT MAX(uid) FROM USER;
SELECT MIN(uid) FROM USER;
SELECT SUM(uid) FROM USER;
SELECT AVG(uid) FROM USER;
SELECT COUNT(uid) FROM USER;

#按照uid降序排列
SELECT * FROM USER ORDER BY uid DESC;
SELECT * FROM USER ORDER BY uid ;