PHP MySQL生成唯一的随机数 [英] PHP MySQL generating unique random number

问题描述

我不明白为什么我的代码无法正常工作.该连接正常工作，但是当我尝试生成一个唯一的随机数并从MySQL检查该数字是否存在时，它仍然会打印出一个随机数，但不是唯一的.有人可以帮我吗? 这是我的代码:

I don't understand why my code isn't working. The connection works and everything else however when I try to generate a unique random number and check from the MySQL if the number is there it still prints out a random number but it's not UNIQUE. Could anyone help me thx? Here's my code:

$num = rand(1,5);
$sel_query  = "SELECT *  FROM  test"; 
$result2 =  $con->query($sel_query);

$i = 1;
for (;$i<2; $i++)
{
    while($row = mysqli_fetch_array($result2))
    {
        if ($row['id'] == $num) 
        {
             $num = rand(1,5);
             $i = 0; 

        }
    }
}   

推荐答案

这应该有效:

$is_unique = false;
$num = false;
while (!$is_unique){
    $num = rand(1,5);
    $sel_query  = "SELECT id from test where id = " . $num; 
    $result2 =  $con->query($sel_query) or die($conn->error);
    if (!mysqli_fetch_array($result2)){
        $is_unique = true;
    }
}
echo "Unique number is " . $num;   

但是，如果没有更多可能的唯一数字，它将永远循环.

But if there aren't any more possible unique numbers, it will loop forever.

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