Insert query not working with MySQL - php

Question

I don't know if wrote something wrong in the query, or if it's a logic error. The problem is on the second to last line.
<?php
include "connectdb.php";
$userId = mysql_real_escape_string($_GET["userId"]);
$q1 = mysql_query("SELECT * FROM visitors WHERE userId='userId'");
$num = mysql_num_rows($q1);
if($num==1){
//user exists, update visits and unique values
$visits = 0;
while($row=mysql_fetch_array($q1)){
$visits = $row["visits"] + 1;
echo $row["visits"] + 1;
}
mysql_query("UPDATE visitors SET visits='$visits',unique='no' WHERE userId='$userId'");
die();
}
//if there is no current visitor
mysql_query("INSERT INTO visitors(userId,visits,unique) VALUES('$userId','1','yes')");
?>
EDIT: userId and visits are both set to INT in the database.

Answer 1

i think first error in in variable name using in $ql and second is $num==1 if in visitors table multiple record of thats user then this condition will be wrong ($num==1) so i think replace it with this ($num>0)
<?php
include "connectdb.php";
$userId = mysql_real_escape_string($_GET["userId"]);
$q1 = mysql_query("SELECT * FROM visitors WHERE userId='$userId' ");
$num = mysql_num_rows($q1);
if($num>0)
{
//user exists, update visits and unique values
$visits = 0;
while($row=mysql_fetch_array($q1))
{
$visits = $row["visits"] + 1;
echo $row["visits"] + 1;
}
mysql_query("UPDATE visitors SET visits='$visits',unique='no' WHERE userId='$userId'");
die();
}
//if there is no current visitor
mysql_query("INSERT INTO visitors(`userId`,`visits`,`unique`) VALUES ('$userId','1','yes') ");
?>

Answer 2

You should add error handling to your sql queries, but the problem (after the correction indicated by #DanielLisik) is the use of a reserved word: unique.
Change your query to:
mysql_query("INSERT INTO visitors(userId,visits,`unique`) VALUES('$userId','1','yes')");
You should also consider changing to PDO or mysqli as the mysql_* functions are deprecated.

Answer 3

1.
Change:
$q1 = mysql_query("SELECT * FROM visitors WHERE userId='userId'");
to:
$q1 = mysql_query("SELECT * FROM visitors WHERE userId=$userId");
2.
Delete the single quotes around $userId in your SQL queries (since it's an INT). It should be like this:
mysql_query("UPDATE visitors SET visits='$visits',`unique`='no' WHERE userId=$userId");
and:
mysql_query("INSERT INTO visitors(userId,visits,`unique`) VALUES($userId,'1','yes')");