php

• php增删改查数据库

$con = mysqli_connect('localhost','root','root','test');

// 查
// $res = mysqli_query($con,"select * from info");

// 增 - 执行成功返回true，执行失败返回false
// $res = mysqli_query($con,"insert info(id,name,age,sex) values(2,'zhaoliu',23,'男')");


// 改 - 执行成功返回true，执行失败返回false
// $res = mysqli_query($con,"update info set sex='女',age=13 where id=4");
// var_dump($res);


// 删 - 执行成功返回true，执行失败返回false
// $res = mysqli_query($con,"delete from info where id=4");
// var_dump($res);

• 注册demo

<?php
header("content-type:text/html;charset=utf8");
echo "<pre>";

$username = $_POST["username"];
$password = $_POST["password"];
$email = $_POST["email"];
$tel = $_POST["tel"];
// 连接数据库
$con = mysqli_connect('localhost','root','root','test');
// 判断用户名
// 执行查询语句
$res = mysqli_query($con,"select * from user where username='$username'");
$row = mysqli_fetch_assoc($res);
if($row){
    echo "用户名被占用了";
}else{
    // 执行添加语句
    $str = "insert user(username,password,email,tel) values
    ('$username','$password','$email','$tel')";
    $bool = mysqli_query($con,$str);
    if($bool){
        // echo "注册成功";
        echo "<script>
            alert('注册成功');
            location.href = 'login.html'
        </script>";
    }else{
        // echo "注册失败";
        echo "<script>
            alert('注册失败');
            location.href = './register.html'
        </script>";
    }
}