php - 检查数据库中是否存在值，如果存在则返回其他值

Question

我正在尝试生成随机代码，然后插入数据库我想生成其他随机代码(如果数据库中存在)

这是我的随机类(class):

    <?php
class code {
    public $code;
    public function mycode(){

        $this->code = rand(1111111,9999999); //7894564

        $this->code = str_replace(0,"A",$this->code);
        $this->code = str_replace(1,"B",$this->code);
        $this->code = str_replace(2,"-",$this->code);
        $this->code = str_replace(3,"C",$this->code);
        $this->code = str_replace(4,"I",$this->code);
        $this->code = str_replace(5,"GB",$this->code);
        $this->code = str_replace(6,"7",$this->code);
        $this->code = str_replace(7,"W4",$this->code);
        $this->code = str_replace(8,"S",$this->code);
        $this->code = str_replace(9,"M",$this->code);
        $this->code = str_replace(10,"RQ",$this->code);

        $this->code = substr($this->code,0,9);

        return $this->code;

    }
}

$class_code = new code();
?>

在这里检查并打印代码

 $code = $class_code->mycode(); 
    $get_code =  mysqli_query($link,"Select * from links WHERE link = '".$code."'");
    $if_exist = mysqli_num_rows($get_code);
                          if($if_exist == 1)
    {
          while($if_exist == 1)
          {
              // Here Return New Code
          }
    } else{
    echo $code;
                }

Answer 1

请检查下面的代码片段。您将能够使用它创建独特的随机代码。如果您有任何疑问，请告诉我。

<?php 
class code {
    public $code;
    public function mycode($link,$length=6){
        //Generating random code
        $characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
        $this->code = '';
        for ($i = 0; $i < $length; $i++) {
        $this->code .= $characters[rand(0, strlen($characters) - 1)];
        }
        //Check generated code is exist in Db or not
        $get_code =  mysqli_query($link,"Select * from links WHERE link = '".$this->code."'");
        $if_exist = mysqli_num_rows($get_code);
        if($if_exist == 1)
        {
            //if code is already exist then recursively call function to generate new unique code.
            $this->mycode($link);
        }
        return $this->code;
    }
}
//create object
$class_code = new code();
//call function to generate unique code.
//$link is the connection
$uniqueCode = $class_code->mycode($link);
?>