Prepared Statements - Select

Dear List - Thanks to all for your responses. Here is another one .... I wish to accomplish the following mysqli_stmt_bind_param($stmt, 'sis', $_POST['Site'], $_POST['MedRec'], $_POST['Sex']); This statemnt was hand coded. I wish to be able to generalize it. Therefore -

        $sql11 = "SELECT Site, MedRec, Fname, Lname, Phone, Height, Sex, Hx, Bday, Age FROM Intake3 where  1 ";

        $allowed_fields = array
            (  'Site' =>$_POST['Site'], 'MedRec' => $_POST['MedRec'], 'Fname' => $_POST['Fname'], 'Lname' => $_POST['Lname'] ,
             'Phone' => $_POST['Phone'] ,  'Height' => $_POST['Height'],  'Sex' => $_POST['Sex'],  'Hx' => $_POST['Hx'],
             'Bday' => $_POST['Bday'], 'Age' => $_POST['Age']  );

    $z0    ='$_POST';
    $z0 .="['Site']";

    $z1    ='$_POST';
    $z1 .="['MedRec']";

    $z2    ='$_POST';
    $z2 .="['Fname']";
        .
        .
        .

    $indeces = array(
        "0" => array
        (
        'tpe'=> 's',
        "val" => $z0
        ),
        "1" => array
        (
        "tpe" => "i",
        "val"=> $z1
        ),
        .

        .

    $binder = array(); //array to hold variables
    $typer = array(); //array to hold variable type
    $position = -1;
    foreach ( $allowed_fields as $key => $val )
    {
        $position = $position + 1;

        if  ($val != '')
        {
            array_push($binder, $indeces[$position]['val']);
            array_push($binder, ", ");
            array_push($typer, $indeces[$position]['tpe']);
            $sql11 .= " AND ($key  = ?) ";
        }

     }
    array_pop($binder);

The above generates the following query: SELECT Site, MedRec, Fname, Lname, Phone, Height, Sex, Hx, Bday, Age FROM Intake3 where 1 AND (Site = ?) AND (MedRec = ?) AND (Sex = ?) //Construct the strings for the mysqli_stmt_bind_param statement $typ2 = implode($typer); $typ3 = "'"; $typ3 .=$typ2; $typ3 .= "'"; $bind3 = implode($binder); //This statement works perfectly. mysqli_stmt_bind_param($stmt, 'sis', $_POST['Site'], $_POST['MedRec'], $_POST['Sex']); //This one fails

    mysqli_stmt_bind_param($stmt, $typ3, $bind3);

With the following error message: Warning: mysqli_stmt_bind_param(): Number of elements in type definition string doesn't match number of bind variables echo "<br />$typ3";'sis' echo "<br /> $bind3"; $_POST['Site'], $_POST['MedRec'], $_POST['Sex'] Help and Advice, please Ethan