CREATE DATABASE mysql_01;
USE mysql_01;
SHOW DATABASES;
DROP DATABASE mysql_01;               
CREATE DATABASE mysql_01;
USE mysql_01;
CREATE TABLE users(
uid INT PRIMARY KEY AUTO_INCREMENT,
friendsname VARCHAR (20),
friendsage INT(2)
);
SHOW TABLES
DESC usres
youxiangAdressyouxiangAdress
INSERT INTO users(uid,friendsname,friendsage,youxiangAdress)VALUES(1,'姬国进',23,'xiaojiji@chinaums.com');
INSERT INTO users(uid,friendsname,friendsage,youxiangAdress)VALUES(2,'周天木',26,'tianmu@chinaums.com');
INSERT INTO users(uid ,friendsname,friendsage,youxiangAdress)VALUES(3,'石浩',25,'shihao@chinaums.com');
INSERT INTO users VALUES (4,'刘昌怀',23,'liuchanghuai@chinaums.com');
INSERT INTO users VALUES(5,'白昂',35,'angbai@chinaums.com');
UPDATE  users SET friendsname='郝翰'WHERE uid=1;
UPDATE users SET friendsname= '宋培栋' WHERE uid =2;
UPDATE users SET friendsage=23 WHERE uid=2 OR uid=3;
DELETE FROM users WHERE uid =2;
SELECT youxiangAdresS FROM USERS;
SELECT *FROM USERS
SELECT friendsname AS '朋友姓名'FROM users
SELECT friendsAge AS '朋友年龄'FROM users;
SELECT *FROM USERS
SELECT *FROM users WHERE friendsage =23;
SELECT *FROM users WHERE friendsage>23;
SELECT *FROM users WHERE  friendsname LIKE'___';
SELECT COUNT(*) FROM users
SELECT COUNT(friendsage)FROM users
SELECT COUNT(friendsname)FROM users
SELECT *FROM users WHERE friendsname LIKE'__';
SELECT SUM(friendsage)FROM users;
INSERT INTO users VALUES (6,'张洪慊',25,'itheima.com');
INSERT INTO users VALUES (7,'周杰伦', 36,'ourjay@chian.com');
SELECT SUM(friendsage)AS'年龄求和',friendsage FROM users;
GROUP BY friendsage;
GROUP BY'年龄求和'DESC ;

还不完美