PHP Mysql If statement not working

Question

Got a issue where if the rows are equal to 0 the else statement is not called. if i type in the correct details on the site, the first condition is met and the xml is displayed, however if the incorrect details are entered, the error xml is not displayed.

echo "<users>"; 
$result = mysql_query("SELECT * FROM `numbers` WHERE `email` = '".$email."' AND `password` = '".$password."'") or die('Invalid query: ' . mysql_error());

if (!$result) die('Invalid query: ' . mysql_error());
while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
{
    if(mysql_num_rows($result) != 0)
    {
        echo "<usercallback>";
        echo  "<id>".$row['id']."</id>";
        //echo  "<number>".$row2['number']."</number>";
        //echo  "<gender>".$row2['gender']."</gender>";
        //echo  "<relationship>".$row2['relationship']."</relationship>";
        echo  "</usercallback>";
    }
    else
    {
        echo "<usercallback>";
        echo  "<id>error</id>";
        echo  "</usercallback>";
    }
}

echo "</users>";

Avoid using the mysql functions, instead use mysqli, it's better in all ways and mysql is on the road to being deprecated — τεκ
– τεκ, Commented Aug 24, 2011 at 14:13

Mithun Satheesh · Accepted Answer · 2011-08-24 12:25:37Z

6

actually you have to put the if mysql_num_rows check outside the while block

echo "<users>"; 
$result = mysql_query("SELECT * FROM `numbers` WHERE `email` = '".$email."' AND `password` = '".$password."'") or die('Invalid query: ' . mysql_error());


if(mysql_num_rows($result) != 0)
    {
    while ($row = mysql_fetch_array($result, MYSQL_ASSOC))
        {       
        echo "<usercallback>";
        echo  "<id>".$row['id']."</id>";
        //echo  "<number>".$row2['number']."</number>";
        //echo  "<gender>".$row2['gender']."</gender>";
        //echo  "<relationship>".$row2['relationship']."</relationship>";
        echo  "</usercallback>";
        }
    }
    else
    {
        echo "<usercallback>";
        echo  "<id>error</id>";
        echo  "</usercallback>";
    }

echo "</users>";

edited Aug 24, 2011 at 12:25

answered Aug 24, 2011 at 11:56

Mithun Satheesh

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5 Comments

cwallenpoole Over a year ago

The mysql_num_rows followed by the while loop is an anti-pattern. Replace it with

$row = mysql_fetch_array($result, MYSQL_ASSOC); if( !$row ){/*handle no results*/} else{do{ /* handle rows */ }while($row = mysql_fetch_array($result, MYSQL_ASSOC));}

Mithun Satheesh Over a year ago

i was unaware of this thing.. i checked in my end and found working.. please suggest me a documentation so that i can understand more.. also it would be helpful if you could edit my answer.

f.ardelian Over a year ago

@cwallenpoole: In my book, do..while loops are anti-patterns, because they often imply code duplication such as the call to mysql_fetch_array() in your example.

Dan Ray Over a year ago

@cwallenpoole - I don't have a problem with how mithunsatheesh wrote it. The idiom of peeling off a row to test for emptiness before entering the loop, on the other hand, makes my skin crawl.

f.ardelian Over a year ago

@mithunsatheesh: Your forgot to remove the or die or move it in the if (!$result) statement below it. It's another code duplication, this time made by the author of the question.

Pradeep · Accepted Answer · 2011-08-24 11:57:30Z

0

while ($row = mysql_fetch_array($result, MYSQL_ASSOC))

If there are no rows then $row will be false and it will never enter the above while loop. So you can not get error message

answered Aug 24, 2011 at 11:57

Pradeep

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Comments

user908378 · Accepted Answer · 2011-08-24 12:02:18Z

0

You check for rows while performing the loop, you should check for the number of rows BEFORE the while loop.

answered Aug 24, 2011 at 12:02

user908378

Comments

Dan Ray · Accepted Answer · 2011-08-24 12:18:28Z

It looks like you're expecting a zero-row response from MySQL to result in an undef $result. That's not what happens. mysql_query() returns null if there was an error. You can test the "truth" of its return value to see if the query ran correctly. If the query results in 0 rows of response, it ran correctly. The value to test, then is mysql_num_rows($result).

However, it can be done simpler. I usually write this like:

$res = mysql_query("SELECT 1");
if (!$res) {
    //do whatever error reporting if the SQL was bad
    //though you should probably deal with any condition that ends up
    //here before you go into production!
}
if (mysql_num_rows($res) == 0) {
    //put out my "no results found" message
}
while ($row = mysql_fetch_assoc($res)) {
    //do my per-row business
}

mysql_fetch_assoc() returns false when there are no (or no more) results to return. So if it's empty, that while loop will never run, so it doesn't need to be inside an else.

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