Query does not insert into database - php

Question

I've made this code but for some reason when i submit the form the data is not inserted to the table name posts. here's my code, i might have a typo or something, it'd be great if someone could have a look.
$fnames = Array("","","","","");
$fcnt = 0;
if (isset($_POST['submit']))
{
$allowedExts = array("gif", "jpeg", "jpg", "pjpeg", "x=png","png",);
// do all 5 files!
for ( $fnum = 1; $fnum <= 5; ++$fnum )
{
$curfile = $_FILES["uploaded_file" . $fnum];
if ($curfile["error"] > 0) {
echo "Return Code: " . $curfile["error"] . "<br>\n";
} else {
$ftype = explode( "/", $curfile["type"])[1]; // get the part after the /
$fsize = $curfile["size"];
if ( in_array($ftype, $allowedExts) && $fsize < 20000000 )
{
echo "Upload: " . $curfile["name"] . "<br>\n";
echo "Type: " . $ftype . "<br>\n";
echo "Size: " . ($fsize/1024) . " KB<br>\n";
echo "Temp file: " . $curfile["tmp_name"] . "<br>\n";
$fname = $_SESSION["userid"] . "_" . $curfile["name"];
if (file_exists("uploads/$fname"))
{
echo "$fname already exists.<br>\n";
} else {
move_uploaded_file($curfile["tmp_name"], "uploads/$fname");
$fnames[$fnum-1] = $fname;
++$fcnt;
}
}
else
{
echo "No valid file in slot $fnum<br>\n";
}
}
}
if ( $fcnt > 1 )
{
$sql = "INSERT INTO posts (picture1, picture2, picture3, picture4, picture5) VALUES( ". "'" . implode("','", $fnames) . "')";
echo "DEBUG SQL: $sql <hr>\n";
mysqli_query($sql);
}
}

Answer 1

With a quick glance:
A) error in your mysqli_query($sql);.
The mysqli_ extensin needs the connection pointer, something like: mysqli_query($dbConn, $sql);
B) Also, modify your query to look like mysqli_query($dbConn, $sql) or die(mysqli_error($dbConn));. It will show you the sql errors, if any.
EDIT 1
If no errors appear after you put the mysqli_error(), then i think your script never gets to the sql part. Something stops it before that if.
Put on top of your script:
error_reporting(E_ALL);
ini_set('display_errors', '1');
and check if any php errors appear on the page.

Answer 2

Most of the time is a string/integer mismatch. Double check all your string escape characters. Copy your final query string and use some external tool to submit the query. You could start hardcoding all your data in the query and then proceed by adding one parameter at a time. Eventually you'll find the field (or fields) that causes the problem.
However, read carefully the error message first instead of guessing blindly what's causing the problem :-)

Answer 3

Make sure your fields count and values count are the same. Also correct this as well:
"'".implode("','", $fnames)."'"
in values passed.