Call PHP function from Javascript to update Database

We need to call a PHP function from a webpage thru Javascript. The users will have 4 buttons to specify their mood. These buttons are mapped to the keyboard keys 'a','s','d' and 'f'. the javascript is working and it's provided. What we need is that whenever the javascript function is invoked, there is an ajax request to a PHP page that will update the database increasing the values of total votes. The total votes tracked are the following: 1) Total votes from the beginning of the tracking 2) Total votes for the current month The database structure is very simple and the structure is provided. Summary of Requirements: 1) Implement the PHP function to be called from Javascript 2) Whatever happens, the request must be performed with ajax in background without reloading the page. 3) In case of PHP errors the page can be reloaded if necessary. In any case, no message should be displayed on the page since there won't be a keyboard connected. 4) a PHP page retrieving the table with the current values, showing a total for all the periods at the bottom. 5) if the month changes, add a new period in the period column, format 'YY-MM' (1803) and restart the counter for the period What is provided: 1) the ZIP with the working prototype for the javascript part, icons and static counters 2) the database sql creating script to see the table how it looks like What is needed: 1) the PHP file adding informations to the database 2) the PHP page with the summary of the values and total 3) modification of the given Javascript to call script at point 1 without page reload (ajax)