ESP8266 and direct comunication with MySQL

Hello,

i've tried to establish a basic comunication to MySQL DB according to this tutorial : Sending data from the ESP8266 to MySQL directly - ioTechProjects
however you can find pretty similar example directly in Arduino IDE....Everything's working fine, i mean the communication to wifi network and database, but if i want to write something with a help of INSERT INTO, i gave an error.
I'm talking about this row : String INSERT_SQL = String("INSERT INTO ") + database + "." + table + " (temperature, humidity, pressure) VALUES (" + temperature + "," + humidity + "," + pressure + ")";
I dont know why? Is there anything wrong with this code? I dont think so...
I've tried to access my DB from console and tried to get the necessary command manually and everything's working....
Any ideas? >]

Thank u very much for helping me