php - SQL syntax error

Im fairly new to both PHP and SQL but what i want is for the details entered into my form to be inserted into a database.

The code i have written works and the data is submitted into the database but there are a couple things not right.

Firstly here is the code;

<?php

include "credentials.php";


function insert_post($cnhost,$cnusername,$cnpassword,$cndatabase,$titlein,$contentin,$comment_optionin) {


    $connect = mysqli_connect($cnhost,$cnusername,$cnpassword,$cndatabase);

if (mysqli_connect_errno($connect))     

{

  echo "Failed to connect to MySQL: " . mysqli_connect_error();

  }else{

  echo "Connection Success! <br>";


$submitpost_query = mysqli_query($connect,"INSERT INTO blog_posts (title,content,comment_option) VALUES ('".$titlein."','".$contentin."','".$comment_optionin."')"); 

if (!mysqli_query($connect,$submitpost_query))
  {
  die('Error: ' . mysqli_error($connect));
  }else{
echo "Post submitted.";


}
    mysqli_close($connect);


}
}

$title = $_POST["title"];
$content = $_POST["content"];
$comment_option = $_POST["comment_option"];


insert_post($host,$username,$password,$database,$title,$content,$comment_option);

?>
Copy code

Although the data is submitted into the database as i want i get the following error;

"Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '1' at line 1"

The $comment_option variable contains the value 1 or 0, depending on which radio button is selected so this error might be referring to this variable but this SQL error is the same whether the value of $comment_option is 1 or 0.

I do see "Connection success!" before this error but do not see "Post submitted" even though the post is actually submitted. Any ideas why?

As well as helping me with this problem i would be very grateful if somebody could give me some general tips to improve what iv wrote. I am a noob so im sure there's a few things that could be improved here!

Thanks very much!