Can't find the right coding for calculation - URGENT!

@michiel.dw

Then you would code something like this…

import wixData from ‘wix-data’;

$w.onReady(function () {

//change element IDs and Field Keys as necessary for your specific website

        $w('#submitButton1').onClick((event) => { 

            
            let chosenDate = $w("#dropdown1").value; 

            console.log(chosenDate); 

            let numberOfTickets = $w("#input1").value; 

            console.log(numberOfTickets); 

            wixData.query("database1") //enter database name here 

                .eq("date", chosenDate) //make sure that you have a field key in your database called date, and the field key is type TEXT  

                .limit(1) 
                .find() 
                .then((noob1) => { 

                    console.log(noob1); 

                    let result = noob1.items[0]; 

                    console.log(result); 

                    let ID = result._id 

                    console.log(ID); 

                    let numberOfTicketsAvailable = result.numberOfTicketsAvailable //make sure that you have a field key in your database called numberOfTicketsAvailable, and the field key is type NUMBER 

                    console.log(numberOfTicketsAvailable); 

                    if (numberOfTicketsAvailable >= numberOfTickets) { 

                        let toUpdate = { 
                            "_id": ID, 
                            "numberOfTicketsAvailable": (numberOfTicketsAvailable - numberOfTickets), 
                            "date": chosenDate, 
                        }; 

                        wixData.update("database1", toUpdate) 
                            .then((noob2) => { 

                                console.log("tickets successfully reserved lad"); 


                                console.log("number of tickets now remaining = ",(noob2.numberOfTicketsAvailable)); 


                           }); 


                               } else { 
                                    console.log("not enough tickets available for your selected date"); 
                                } 

                            }) 

                }) 

        })