How to get variable outside mysql scope in node.js?

Question

Node.js

var line_last_id = "SELECT MAX(id) FROM table_name"; 

conn.query(line_last_id, function(err, result) {
var last_id = result[0]['MAX(id)']);  			
});

console.log(last_id);

How to get last_id for area conn.query? Inside is displayed, outside is no longer there. Tried via push, doesn't work either

Answer 1

Decided so

function getLastId(){
return new Promise(function(resolve, reject) {
var line_last_id = "SELECT MAX(id) FROM table_name"; 
conn.query(line_last_id, function(err, result){                                                
resolve(result[0]['MAX(id)']);
})
})
}

getLastId().then((lastid) => console.log(lastid));

Answer 2

the result of qwery is asynchronous and is passed to the callback, it’s not in your case, but in general you need to learn js
then promises and async functions, after that it will turn out as you want.