如何处理PHP中sql查询的单个结果？

Question

I am using the stored $_SESSION username (stored in the $username variable) to obtain the user's id using the following query in PHP:

$query = mysql_query("SELECT id FROM users WHERE username = '".$username."'");

I then process the query result as follows:

$userid = mysql_fetch_row($query);

Because I am logged in as a demo user, the user id that this query should return is: 12. However, when I echo $userid['id'] I get this output:

1111

Is this not a proper way of processing the data from the query? Should I be using mysql_fetch_row() if I am only expecting a single result?

I have also tried running the query in PHPMyAdmin and it returns the expected result just fine.

Answer 1

fetch the results using:

    $query="SELECT id FROM users WHERE username ='$username'";
    $res=mysql_query($query);
    while($row=mysql_fetch_row($res))
    {
                $id=$row[0]; //change to the column number you are using to store id
    }

Answer 2

try this

   while($userid = mysql_fetch_array($query))
    {
      echo $userid['id'].'<br />';
    }

Answer 3

Your query is vulnerable to SQL injection attacks and you are using deprecated libraries which will be removed from future versions of PHP.

I recommend moving to mysqli ( documentation ), which will help to protect you from injection attacks with its prepared statements ( documentation ).

Your query appears correct. If you run SELECT id FROM users WHERE username = 'demo' in PHPMyAdmin or SQL command line, what do you get? Is username a UNIQUE field or do you have two accounts called demo ?