- implode: documentation ( source)
- array_keys: documentation ( source)
<?php
$data = array( 'coluna' => 'valor', 'coluna2' => null, 'coluna3' => 123 );
$cols = implode( ', ', array_keys( $data ) );
$values = implode( ', ', $data );
echo "INSERT INTO table ($cols) VALUES ($values)";