For all:
all the "%" do is tell MySQL it is a wild card. So "am" with "%am%" pulls up anything with any number of letters before the combo "am" and any number of letters after:
name - n am e
tame - t am e
madam - mad am
ambulance - am bulance
understand? So if you're searching the database for a userid, you do not want the LIKE scenario, you want the normal "userid" not, "%userid%".
Furthermore, "%am" will pull only words beginning with anything but ending with am, like "sam", and same as the other way "am%" pulls words like "ambuleance".
For your search page, if you only want one result, add this line to your SQL query: "LIMIT 1"
This way it will only return one result and not waste memory holding the other 200 results that are being unused.
For homienick
So, following the code above as I am not a PHP programmer, use it like below to pull your users info:
<?php
$userid = $_POST["userid"];
mysql_connect ("localhost", "myuser", "mypassword");
mysql_select_db ("mydatabase");
$query = "SELECT mycolumn FROM mytable WHERE mycolumn=$userid"
$result = mysql_query ($query);
if ($result) {
//if this userid exists, do your coding here
}else{
//if this userid does not exist, do your coding here
}
?> 
