PHP not returning false value - php

Question

I have written a piece of code for coupon. whenever I use the function to check if the Coupon Code exists, it returns true and prints the statement. But I can't get the false return and cannot get the statement printed for false case.
function db_connect() {
static $connection;
if (!isset($connection)) {
$connection = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);
}
if ($connection === false) {
return mysqli_connect_error();
}
return $connection;
}
function db_query($query) {
$connection = db_connect();
$result = mysqli_query($connection, $query);
return $result;
}
function db_error() {
$connection = db_connect();
return mysqli_error($connection);
}
function db_select($query) {
$rows = array();
$result = db_query($query);
if ($result === false) {
return false;
}
while ($row = mysqli_fetch_assoc($result)) {
$rows[] = $row;
}
return $rows;
}
function db_rows($query) {
$result = db_query($query);
if ($result === false) {
return false;
}
$total_rows = mysqli_num_rows($result);
return $total_rows;
}
function couponExists($cc) {
$results = db_rows("SELECT * from ms_coupons where coupon_code='".$cc."'") or die(db_error());
if ($results > 0) {
return true;
} else {
return false;
}
}
DB table : ms_coupons
coupon_id coupon_code
1 CODE50
check_coupon.php
$coupon = $_REQUEST['coupon_code'];
if (!couponExists($coupon)) {
echo "Does not exist!";
} else {
echo "Coupon exists!";
}
when i supply coupon_code as CODE50 it prints, Coupon exists! but when i supply something different like CODE51 then the pays prints nothing.

Answer 1

Your problem is with this line in your code:
$results = db_rows("SELECT * from ms_coupons where coupon_code='".$cc."'") or die(db_error());
db_rows function returns number of rows, in your case it can be only two values - 1 or 0. If db_rows return 0 your script executes the die(db_error()) part (but there is no mysqli_error).
Remove the or die(db_error()) part, like this:
$results = db_rows("SELECT * from ms_coupons where coupon_code='".$cc."'");
If you want to check for mysqli_errors, move it to your db_query function.