PHP警告：mysql_fetch_assoc（）期望参数1是资源，布尔值给出

Question

网页没有死亡，它只显示Warning。 请告诉我在这段代码中的问题。谢谢。

<?php 

$connect = mysql_connect('localhost','root','') || die("Error"); 
$selectDB = mysql_select_db('mydb') || die("Error"); 

$query = "SELECT * FROM user_login WHERE ID='2';"; 
$fetch = mysql_query($query) || die("Error"); 

while ($row = mysql_fetch_assoc($fetch)){ #problem is somewhere here 
    echo $row['User_Name']; 
    echo $row['Password']; 
    echo $row['Gender']; 
    echo $row['ID']; 
} 

?> 

给出的警告是：

mysql_fetch_assoc（）预计参数1是资源，布尔给出

Answer 1

<?php 
    $connect = mysql_connect('localhost','root','') || die("Error"); 
    $selectDB = mysql_select_db('mydb') || die("Error"); 

    $query = "SELECT * FROM user_login WHERE ID='2';"; 

    $fetch = mysql_query($query) || die("Error"); 
    $count = count($fetch); 

    if($count>0) 
    { 
     while ($row = mysql_fetch_assoc($fetch)) 
     { #problem is somewhere here 
      echo $row['User_Name']; 
      echo $row['Password']; 
      echo $row['Gender']; 
      echo $row['ID']; 
     } 
    } 
    else 
    { 
     echo 'No Item to select'; 
    } 
?> 

警告
此扩展已被弃用从PHP 5.5.0开始，并将重新开始未来感动。相反，应该使用MySQLi或PDO_MySQL扩展名。有关更多信息，另请参阅MySQL: choosing an API指南和相关常见问题解答。