Juiste query voor heen en terug

 SELECT * FROM tabel1 t1
JOIN tabel2 t2
ON t1.id = t2.postid
WHERE t2.value REGEXP '^[^0-9]+$';

SELECT * FROM tabel1 t1
JOIN tabel2 t2
ON t1.id = t2.value
WHERE t2.value REGEXP '^[0-9]+$';

 <?php
$db = new mysqli ('localhost', 'user', 'password', 'database' );

$query = "SELECT * FROM tabel1 t1
JOIN tabel2 t2
ON t1.id = t2.postid
WHERE t2.value REGEXP '^[^0-9]+$';";

$result = $db->query( $query );

while ( $row = $result->fetch_object() )
{
	echo '<pre>' . print_r( $row, TRUE ) . '</pre>';
	$product = $row;
}

echo '<pre>' . print_r( $product, TRUE ) . '</pre>';

$query = "SELECT * FROM tabel1 t1
JOIN tabel2 t2
ON t1.id = t2.value
WHERE t2.value REGEXP '^[0-9]+$';";

$result = $db->query( $query );

while ( $row = $result->fetch_object() )
{
	echo '<pre>' . print_r( $row, TRUE ) . '</pre>';
	$product->afbeelding = $row->naam;
}

echo '<pre>' . print_r( $product, TRUE ) . '</pre>';

echo '<table border="1">';

$keys = array_keys( (array)$product );

echo '<tr>';

for ( $i = 0; $i < count($keys); $i++ )
{
	echo '<th>' . $keys[$i] . '</th>';
}

echo '</tr>' . PHP_EOL . '<tr>';

foreach (  $product as $key => $value )
{
	echo '<td>' . $value . '</td>';
}

echo '</tr>';

echo '</table>';

?>

SELECT t1.naam, t2.value AS kleur, t1F.naam AS foto
FROM tabel1 t1
JOIN tabel2 t2 on t2.postid = t1.id AND NOT t2.value REGEXP '^[^0-9]+$'
JOIN tabel2 t2F on t2F.postid = t1.id AND t2F.value REGEXP '^[^0-9]+$'
JOIN tabel1 t1F on t1F.id = t2F.value

WHERE tabel1.id = 250