初学数据库，记录一些简单命令 ，用于备忘.
命令行下 创建 database:
C:/Program Files/MySQL/MySQL Server 5.5/bin>mysql.exe -uroot -pg131517 //进入时省略了host参数,默认是'localhost'。 mysql> create database twbook; mysql> create database twbook2; mysql> show databases; mysql> drop database twbook2;//删除 mysql> show databases; mysql> use twbook;
命令行下 添加 table:
mysql> create table stu(id int unsigned primary key,name char(50)); mysql> show tables; //mysql> drop table stu;删除它 mysql> describe stu;
命令行下 添加 一些对象:
mysql> insert into stu values(33,'zhong'); mysql> insert into stu values(32,'tang ding hao');
命令行下 select的使用：
mysql> select id from stu; mysql> select name,id from stu; mysql> select * from stu; mysql> select * from stu where id = 33; mysql> select * from stu where name = 'zhong'; mysql> select * from stu where name = "zhong"; mysql> select * from twbook.stu where name = 'zhong'; mysql> select * from stu where name like("% hao"); //简单模糊 查找 一个叫什么 hao 的人 mysql> select * from twbook.stu order by id; //按元素排序 mysql> select * from twbook.stu order by id desc; mysql> select * from twbook.stu order by (-id); //指定按照descending排序 //二者等价 mysql> select avg(id) from stu; //利用avg()命令函数 求stu的id 的平均数
命令行下 删除对象：
mysql> delete from stu where id = 33;
命令行下 删除table：
mysql> drop table stu;
php脚本 开始使用:
//以下是php里面: @ $aaa = new mysqli('localhost','root','g131517','twbook'); if(mysqli_connect_errno()) { echo "<p> NO!!! </p>"; exit; }
php脚本 插入数据:
$num = 12; $urname = $_POST['urname']; $qqqq = "insert into stu values(".$num.",'".$urname."')"; //echo $qqqq; $result = $aaa->query($qqqq); if($result) { echo "aaaaaaa"; }
(注意上例 固定 $num = 12;而stu的第一个属性id是primary key .所以只能 插入 一次)
php脚本 读入数据:
$query = "select * from stu"; $result = $aaa->query($query); $num = $result->num_rows; echo "<p>有 $num 个:</p>"; for($i = 0 ; $i< $num ; $i++) { $row = $result->fetch_assoc(); echo "<p> "; echo $i ; echo ' : '; echo $row['name'] ; echo "</p>"; } $result->free();
顺便 由于我 的php文件用记事本 gb2312中文编码 写，所以经常要添加：
<head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>标题</title> </head>
