error

<?php
require_once('header.php'); // include header file
require_once('connectvars.php'); // include connections to database
?>

<h2>Input Listing</h2>
<?php
	$output_form = true; // declares a flag to test whether or not to show the form
	$address = NULL;
	$price = NULL;
	$bedroom = NULL;
	$bath = NULL;
	$sqft = NULL;
	$year = NULL;
	$pool = 0; // initialization for checkbox
	$basement = 0; // initialization for checkbox
	$fence = 0; // initialization for checkbox
	$featured = NULL;

	if ( isset($_POST['submit']) ) {
	// condition based on whether or not the user submits form

	// php variable assignments to names used in HTML file
	$address = $_POST['address']; // street address
	$price = $_POST['price']; // price
	$bedroom = $_POST['bedroom']; // number of bedrooms
	$bath = $_POST['bath']; // number of baths
	$sqft = $_POST['sqft']; // sq. ft.
	$year = $_POST['year']; // year built

	if (isset($_POST['pool'])) {
		$pool = $_POST['pool']; // pool
	}

	if (isset($_POST['basement'])) {
		$basement = $_POST['basement']; // finished basement
	}

	if (isset($_POST['fence'])) {
		$fence = $_POST['fence']; // fenced in yard
	}

	if (isset($_POST['featured'])) {
		$featured = $_POST['featured']; // featured listing
	} else {
		$featured = NULL;
	}

	$output_form = false; // will only change to TRUE based on validation.

	// Validation of inputs, minimum reqs: street address and price.

	if ( empty($address) ) {
		echo "You must input the listing's Street Address.<br />"; // Validation to include street address.
		$output_form = true; // will print form
	}

	if ( empty($price) ) {
		echo "You must input the listing's price.<br />"; // Validation to include the listing's price.
		$output_form = true; // will print form
	}

	if ( !is_numeric($price) ) {
		echo "Listing price must be a numeric value.<br />"; // Validation to make numeric.
		$output_form = true; // will print form
	}

	// Once everything in form is correct, run
	if ( !empty($address) && !empty($price) && is_numeric($price) ) {

		// Connect to database
		$dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME)
		  or die('Error connecting to MySQL server.'); // terminates code if failed.

		// creates the SQL query and stores as string in a PHP variable
		$query = "INSERT INTO details (address, price, bedroom, bath, sqft, year, pool, basement, fence, featured) " .
		"VALUES ('$address', '$price', '$bedroom', '$bath', '$sqft', '$year', '$pool', '$basement', '$fence', '$featured')";




	    // issues the query using the msqli_query function that allows it to add data to the database table
		$result = mysqli_query($dbc, $query)
		  or die('Error querying database.'); // terminates if failed

		mysqli_close($dbc);  // close database connection

		// Output for data submitted, verifies that information has been received and processed by system.
		echo '<h3>Your listing has been input into the system.</h3><br/>';
	} // end of if statement that allows run if form is correct
} // end of isset condition that was based on whether or not the form was submitted

if($output_form) { // only show the form if user has error or not submitted.
?>

<!-- load form and use self-referencing PHP variable. -->
<br />
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
	<label for="address">Street Address:</label>
	<input type="text" id="address" name="address" value="<?php echo $address; ?>" /><br />
	<label for="price">Price:</label>
	<input type="text" id="price" name="price" value="<?php echo $price; ?>" /><br />
	<label for="bedroom">Number of Bedrooms:</label>
	<input type="text" id="bedroom" name="bedroom" value="<?php echo $bedroom; ?>" /><br />
	<label for="bath">Number of Bathrooms:</label>
	<input type="text" id="bath" name="bath" value="<?php echo $bath; ?>" /><br />
	<label for="sqft">Sq. Footage:</label>
	<input type="text" id="sqft" name="sqft" value="<?php echo $sqft; ?>" /><br />
	<label for="year">Year Built:</label>
	<input type="text" id="year" name="year" value="<?php echo $year; ?>" /><br />
	<label>Extras:</label>
	<input type="checkbox" name="pool" style="width: auto" value="1" <?php if ($pool) echo "checked"; ?> > Pool
	<input type="checkbox" name="basement" style="width: auto" value="1" <?php if ($basement) echo "checked"; ?> > Finished Basement
	<input type="checkbox" name="fence" style="width: auto" value="1" <?php if ($fence) echo "checked"; ?> > Fenced-in Yard<br />
	<label for="featured">Featured:</label>
	<input type="radio" name="featured" value="yes" <?php if ($featured == "yes") echo "checked"; ?> > Yes
    <input type="radio" name="featured" value="no" <?php if ($featured == "no") echo "checked"; ?> > No <br />
	<input type="submit" value="Submit" name="submit" />
</form>
<?php } // closes the condition related to output_Form, before loading form
require_once('footer.php');
?>