NodeJS and MYSQL Issue - mysql

Question

My code is supposed to retrieve the "DropsRemaining" for a user ID (which it does successfully) and then -1 from the number it retrieves. When retreiving the data it returns this string "[ RowDataPacket { DropsRemaining: 5 } }" however the end of the code does not -1 from the DropsRemaining it instead sets the DropsRemaining to -1. If anyone can help fix this I'd really appreciate it.
var sql = "SELECT DropsRemaining FROM UserData WHERE DiscordID LIKE " + message.author.id;
var DropCount = [];
connection.query(sql, function (err, result) {
if (!err)
setValue(result);
else
console.log("No Information For That User Found");
});
function setValue(value) {
DropCount = value;
console.log(DropCount);
};
//Remove drop from user
DropCount = DropCount - 1;
var sql = "UPDATE UserData SET DropsRemaining = " + DropCount + " WHERE DiscordID = " + message.author.id;

Answer 1

The problem is that the order you write your Javascript code is not exactly how it is performed in the end.
When you call the connection.query() function, the next line of code does not necessarily already have the result of that function.
I would recommend you to have a look on this book series, they have really good explanations about those characteristics.
Probably the following code will output the expected response. Notice that I nested the code, therefore I can control the flow properly.
var sql = "SELECT DropsRemaining FROM UserData WHERE DiscordID LIKE " + message.author.id;
// Get the DropsRemaining
connection.query(sql, function (err, result) {
if (!err) {
// No errors in the query, decrement the Drops
decrementDrop(result);
} else {
console.log("No Information For That User Found");
}
});
function decrementDrop(dropsAvailable) {
var dropsRemaining = dropsAvailable - 1;
var updateSql = "UPDATE UserData SET DropsRemaining = " + dropsRemaining + " WHERE DiscordID = " + message.author.id;
// Update the DropsRemaining column to the dropsRemaining, i.e., decrement the DropsRemaining column value
connection.query(updateSql, function (err, result) {
if (!err) {
console.log("DiscordID = " + message.author.id +" has " + dropsRemaining + " drops remaining")
} else {
console.log("Error!");
}
});
}