$con->准备与$con->sqli->准备之间的区别

Question

我总是被教导和使用$con->准备准备好的陈述。但是，本文的两个答案发布了人们使用$con->sqli->prepare。我还看到其他一些人在其他文章中使用它。

这是值得关注的吗？有什么区别？

Answer 1

通常有些人用连接的构造函数制作数据库连接类。这意味着当您初始化该类的对象时，构造函数将自动执行。
例如，这里是数据库类

<?php
class db
{
    public $conn;
    public function __construct()
    {
        $this->conn=mysqli_connect("localhost","root","","prepared");//A constructor is a function that is executed after the object has been initialized (its memory allocated, instance properties copied etc.). Its purpose is to put the object in a valid state.
        if($this->conn)
        {
            echo "";
        }
        else{
            echo $this->conn->error;
        }
    }
}
$db = new db();
?>

儿童类

include("db.php");
 class childclass extends db
{


public function database_query()//here you don't need to put $conn in parameters
 {
    $sql = "SELECT * FROM table";
    $result = $this->conn->query($sql);//Here you can see how we can call conn from db class
    print_r($result);


 }
}

我希望你明白我的意思。