web前端增加后台数据库

//连接数据库
$con = mysqli_connect('localhost','root','','test');
//设置编码格式
mysqli_set_charset($con,"utf8");
//检查连接是否成功
if (!$con) {
    die('Connect Error (' . mysqli_connect_errno() . ') ' . mysqli_connect_error());
}

$name = $_POST['name'];
$age = $_POST['age'];
$sex = $_POST['sex'];
$insert = "INSERT INTO user (name, age, sex) VALUES ('$name', '$age', '$sex')";
if ($con->query($insert) === TRUE) {
    echo "插入成功！";
} else {
    echo "Error: " . $insert . "<br>" . $con->error;
}

$id = $_GET['id'];
$delete = "DELETE FROM user WHERE id=$id";
if ($con->query($delete) === TRUE) {
    echo "删除成功！";
} else {
    echo "Error: " . $delete . "<br>" . $con->error;
}

$id = $_POST['id'];
$name = $_POST['name'];
$age = $_POST['age'];
$sex = $_POST['sex'];
$update = "UPDATE user SET name='$name', age='$age', sex='$sex' WHERE id=$id";
if ($con->query($update) === TRUE) {
    echo "修改成功！";
} else {
    echo "Error: " . $update . "<br>" . $con->error;
}

$sql = "SELECT * FROM user";
$result = mysqli_query($con,$sql);

if (mysqli_num_rows($result) > 0) {
    while($row = mysqli_fetch_assoc($result)) {
        echo "ID:".$row["id"]." - Name:".$row["name"]." - Age:".$row["age"]." - Sex:".$row["sex"]."<br>";
    }
} else {
    echo "0 结果";
}
mysqli_close($con);