What's wrong with my data submisson system[one button, 2 fields] - php

Question

I am setting up my custom blog's basic submission system.
This is the PHP section of it that I try to submit the inserted data into the database
<?php
session_start();
if(!isset($_SESSION['user_id'])){
header('Location: login.php');
exit();
}
include('../includes/db_connect.php');
if(isset($_POST['submit'])){
$newTitle = $_POST['newTitle'];
$newPost = $_POST['newPost'];
$my_date = date("Y-m-d H:i:s");
if(!empty($newPost))
if(!empty($newTitle)){
$sql="INSERT INTO posts (title, body)
VALUES($newTitle, $newPost)";
$query = $db->query($sql);
if($query){
echo "Post entered to database";
}else{
echo "Error Submitting the data";
}
}
}
?>
Then There is the submission form, I am pretty sure this is the faulty end for some reason, but I cannot find out why.
<form action="<?php echo $_SERVER['PHP_SELF']?>"name="newTitle" method="post">
<form action="<?php echo $_SERVER['PHP_SELF']?>" method="post">
<p>Title:</p><br><input type="text" name="newTitle">
<textarea name="newPost" cols="110" rows="25"/></textarea><br>
<label for="newPost">Add New Post</label><input type="submit" name="submit" value="submit"/>
</form>
This is the database's table:
post_id (A_I)
user_id
title
body
category_id
posted(datetime)
Bear in mind that I am a rookie in this area, so don't be too harsh :)

Answer 1

Use single quote for strings:
$sql="INSERT INTO posts (title, body) VALUES ('$newTitle', '$newPost')";
//^ ^ ^ ^
Notice:
Try to use PDO and param binding in your projects to prevent sql injection.
Nice Tutorial about PDO

Answer 2

Use single form tag only:
<form action="<?php echo $_SERVER['PHP_SELF']?>" method="post">
<p>Title:</p><br><input type="text" name="newTitle">
<textarea name="newPost" cols="110" rows="25"/></textarea><br>
<label for="newPost">Add New Post</label>
<input type="submit" name="submit" value="submit"/>
</form>
And in your php code, you can check youe data by using isset() function
if(isset($_POST['submit'])){
if(isset($_POST['newTitle']) && ($_POST['newPost']))
$newTitle = $_POST['newTitle'];
$newPost = $_POST['newPost'];
$my_date = date("Y-m-d H:i:s");
$sql="INSERT INTO posts (title, body)
VALUES('$newTitle', '$newPost')"; //use variable in single quote.
$query = $db->query($sql);
if($query){
echo "Post entered to database";
}else{
echo "Error Submitting the data";
}
}