How to implement multiple find boxes just fill in at least one find content to find

How to implement multiple find boxes just fill in at least one find content to find
Apply.html


<title>A new application for a classroom</title>

Crms-new Classroom Entry

2.php



<title>A new application for a classroom</title>

Crms-new Classroom Entry Results

Create short variable names
$Cno =$_post[' Cno '];
$CID =$_post[' CID '];

if (! $Cno) {$Cno = "%";}
if (! $CID) {$CID = "%";}

if (!GET_MAGIC_QUOTES_GPC ()) {
$Cno = Addslashes ($Cno);
$CID = Addslashes ($CID);
}

$con = mysql_connect ("localhost", "root", "");
Connect via server locahost, user name is root, no password

if (! $con)
{
Die (' Could not connect: '. Mysql_error ());
}
mysql_select_db ("CRMs", $con);

$search _classroom = "SELECT * FROM Use2
WHERE Cno like ' {$Cno} ' and CID like $CID ";
$result = mysql_query ($search _classroom, $con);

while ($row = Mysql_fetch_array ($result))
{
echo $row [' Cno '];
echo $row [' CID '];
echo "
";
}
Mysql_close ($con)
?>



Why this cannot be achieved when the classroom ID or course ID is not filled out, still can successfully search. I have already written if (! $Cno) {$Cno = "%";}
if (! $CID) {$CID = "%";} If you do not fill in the wildcard character, and the query is also used like (if the query as if all to = is successful). Why? Online and so on!

------Solution--------------------
Because you use like. Check out the MySQL manual.

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