问Mysqli选择？(bind_param)

EN

//THIS WORKS
if ($stmt = mysqli_prepare($mysqli, "SELECT $garment FROM user WHERE uid=?")) {
mysqli_stmt_bind_param($stmt, "i", $uid);
mysqli_stmt_execute($stmt);
mysqli_stmt_bind_result($stmt, $total);
mysqli_stmt_fetch($stmt);
mysqli_stmt_close($stmt);
}

//DOESN'T WORK - $total returns the value of $garment
if ($stmt = mysqli_prepare($mysqli, "SELECT ? FROM user WHERE uid=?")) {
mysqli_stmt_bind_param($stmt, "si", $garment, $uid);
mysqli_stmt_execute($stmt);
mysqli_stmt_bind_result($stmt, $total);
mysqli_stmt_fetch($stmt);
mysqli_stmt_close($stmt);
}