<?php
$servername="pepito";
$username="alicia";
$password="conejo";
$dbname="zoo";

$conn = new mysqli( $servername, $username, $password, $dbname);
if ($conn->connect_error)
    die("Fallo de conexi&oacute;n: ".$conn->connect_error);
else
    echo    "Usuario ".$username
        ." conectado a la base de datos ".$dbname
        ." del servidor ".$servername."<br>";

$sql="select * from animales";
$sexo=$_POST["sexo"];
if ($sexo) $sql=$sql." where sexo='".$sexo."'";
echo "Consulta SQL: ".$sql."<br>";

$result=$conn->query($sql);
echo $result->num_rows." filas<br>";

if ($result->num_rows > 0) {
    echo "<table><tr>";
    $fieldinfo=mysqli_fetch_fields($result);
    foreach ($fieldinfo as $val)
        echo "<th>{$val->name}</th>";

    echo "</tr>";

    $n=$result->field_count;
    while ($row = $result->fetch_array(MYSQLI_NUM)) {
        echo "<tr>";
        for ($i=0; $i < $n; $i++)
            echo "<td>".$row[$i]."</td>";
        echo "</tr>";
    }
    echo "</table>";
} else
    echo "0 filas de resultado";

$conn->close();
?>