php 后台数据库与前台请求结合

<code><?php
    // GET请求(默认)
/*
    // <span>$_GET</span>获取 get请求中参数值
    <span>$username</span> = <span>$_GET</span>[<span>"userName"</span>];
    <span>$password</span> = <span>$_GET</span>[<span>"password"</span>];
    <span>echo</span>(<span>"username:"</span>.<span>$username</span>.<span>"  password:"</span>.<span>$password</span>);
*/
    // POST请求,打开网页没值
    // 获取 body 体中,这两个变量的值
/*
    <span>$username</span> = <span>$_POST</span>[<span>"username"</span>];
    <span>$password</span> = <span>$_POST</span>[<span>"password"</span>];
    <span>if</span>(<span>$username</span> == <span>"houzhichao"</span> && <span>$password</span> == <span>12345</span>) {
        <span>$dic</span> = array(<span>"code"</span>=><span>200</span>,<span>"message"</span>=><span>"登录成功"</span>);
        <span>echo</span>(json_encode(<span>$dic</span>));
    } <span>else</span> {
        <span>$dic</span> = array(<span>"code"</span>=><span>404</span>,<span>"message"</span> =><span>"登录失败"</span>);
        <span>echo</span>(json_encode(<span>$dic</span>));
    }
*/

// 注册结合数据库去使用,将前台写的东西,写到服务器数据库中
// <span>1</span>.获取 用户 GET体中参数的值
<span>$username</span> = <span>$_GET</span>[username];
<span>$password</span> = <span>$_GET</span>[password];
// <span>2</span>.使用数据库
// (<span>1</span>)连接数据库 mysql_connect
// 参数<span>1</span>:服务
// 参数<span>2</span>:登录数据库的用户名,我们选的是根用户
// 参数<span>3</span>:密码,当为空,可以省
// ** 有个返回值 BOOL
<span>$islink</span> = mysql_connect(<span>"127.0.0.1"</span>,<span>"root"</span>,<span>""</span>);
<span>if</span>(<span>$islink</span>) {
    <span>echo</span>(<span>"数据库连接成功<br>"</span>);
    // (<span>2</span>)选择数据库  mysql_select_db
    mysql_select_db(<span>"DataBase"</span>);
    // (<span>3</span>)查询数据库中的用户表,有没有当前的用户名;返回值(指令集 or BOOL)  mysql_query
    // results是一个 数组(都是记录),查询全部的内容
    <span>$results</span> = mysql_query(<span>"select username from users"</span>);
    <span>while</span>(<span>$row</span> = mysql_fetch_array(<span>$results</span>)) {
        // 判断 row 记录中的用户名是否跟当前注册的用户名一样
        <span>if</span>(<span>$row</span>[<span>"username"</span>] == <span>$username</span>) {
            <span>echo</span>(<span>"注册失败,用户名已存在<br>"</span>);
            <span>return</span> ;
        }
    }
    // 可以进行注册操作
    // 相当于向 users 的表中,插入数据
    <span>$result</span> =  mysql_query(<span>"insert into users(username,password)values('<span>$username</span>','<span>$password</span>')"</span>);
    <span>if</span>(<span>$result</span>) {
        <span>echo</span>(<span>"注册成功<br>"</span>);
    } <span>else</span> {
        <span>echo</span>(<span>"注册失败<br>"</span>);
    }
} <span>else</span> {
    <span>echo</span>(<span>"链接失败"</span>);
}


?></code>