<?php
require("sql.php");
        $sqlvenda = "SELECT * FROM venda";
        $qr = mysql_query($sqlvenda) or die (mysql_error());
        while($ln = mysql_fetch_assoc($qr)){
        $id = $ln['id'];
        $nome = $ln['nome'];
        ?>
        <?php echo $nome; ?></h2><br>
<a href="?pagina=carrinho&acao=add&id=<?php echo $id; ?>" />Comprar</a>
        <?php } ?>