error check - mysql - php

What's the best way to do an error check to see if the user ID exists?  if it doesn't exist, come back with "this user ID doesn't exist, try again".

ideas?  suggestions?

//GET ID # FROM USERS TABLE
$getIDsql = "select id from users where user_login = '$username'";
$getIDquery = mysql_query($getIDsql) or die ("Error in query: $getIDsql. ".mysql_error());
$getIDresult =  mysql_result($getIDquery, 0, 'id');
LVL 1
bschwartingAsked:
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Guy Hengel [angelIII / a3]Connect With a Mentor Billing EngineerCommented:
use the mysql_num_rows() function:
//GET ID # FROM USERS TABLE
$getIDsql = "select id from users where user_login = '$username'";
$getIDquery = mysql_query($getIDsql) or die ("Error in query: $getIDsql. ".mysql_error());
if (mysql_num_rows($getIDquery) == 0)
{
  echo "this user ID doesn't exist, try again.";
}
else
{
   $getIDresult =  mysql_result($getIDquery, 0, 'id');
    ...
 }

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bschwartingAuthor Commented:
I also need to set my variable $getIDresult to 1 if there isn't a result, how can i add this?

if (mysql_num_rows($getIDquery) == 0)
{
  echo "this user ID doesn't exist, try again.";
  $getIDresult = '1';
}

This doesn't seem to work.
0
 
bschwartingAuthor Commented:
oops, had the wrong variable. and another piece of bad code.  that fixed it!
if (mysql_num_rows($getIDquerycompare) == 0)
{
  echo "this user ID doesn't exist, try again.";
  $getIDresultcompare = '1';
}

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0
 
Guy Hengel [angelIII / a3]Billing EngineerCommented:
>This doesn't seem to work.
in how far? the code looks fine...
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