unexpected error message in php form (SQL syntax error)

Question

I have made a simple php cms form with database but it does not work properly when I want to submit the form with some dummy data! I don\'t know why it happens & also I adde

Answer 1

writing if statement in this way is better

// this not always works
if ($post_title=='' or $post_keywords='' or $post_content='' or $post_author=''){
        echo '';
    }

// yeah much better 
 if (empty($post_title) || empty($post_keywords) || empty($post_content) || empty($post_author)){
            echo '';
        }

and sql mistake most probably because of here

'$post_keywords','$post_content')";

$post_keywords and $post_content is null or empty