This is bad news if it's memory problem. Yes, sorry I forgot to mention, it's UNO.
Maybe I will have to abandon this solution, since this mysql library takes some resources. So, I have only the php solution.
What you don't know is, that besides this code, I will have more on this arduino. This sketch was just for testing to see if it works. Those float variables that represents temperature and humidity, arrived there by the help of some wifi modules... so I must add some aditional libraryies: VirtualWire, LiquidCrystal_I2C.
So I am preety sure the space it's too low... though the IDE showed me that I have left some memory for program space and variables to spare...
Thank you!