我没有得到任何返回值...为什么？

Question

是的，它连接到数据库，其他一切正常。我似乎无法从数据库中拉出传递，显示没有返回echo

 <?php

$username="test";
    include("db.php");

     $con=mysql_connect($server, $db_user, $db_pwd) //connect to the database server
or die ("Could not connect to mysql because ".mysql_error());

    mysql_select_db($db_name)  //select the database
    or die ("Could not select to mysql because ".mysql_error());

$query="select password from ".$table_name." where username='$username'";
            $result=mysql_query($query,$con) or die('error');
        while ($row = mysql_fetch_assoc($result));
        $un_pass_s1=$row['password'];
    echo $un_pass_s1;
?>

Answer 1

while ($row = mysql_fetch_assoc($result));循环，直到$row为假。循环体是一个空的语句;。您需要将访问$row 的代码放在循环中，而不是在循环之后。

Answer 2

$sql=mysql_query("select password from ".$table_name." where username='$username'");

while($row=mysql_fetch_array($sql))
{
$un_pass_s1=$row['password'];
}
echo "value=".$un_pass_s1;