Help Me to Finish function Only Returns true o false

[beenii]

hi i made this function:
working perfect, only get false, want return true or false and optimize i new in create functions.

function getSerialValor(serial)
assert(serial,'Serial is nil' and false)
local a = db.getResult("SELECT `valor_points` FROM `serial_numbers` WHERE `serial` = '"..serial.."';")
if a:getID() ~= -1 then
return a:getDataInt("valor_points") or 0, a:free()
else
return false
end
end