How to use trigger to perform addition from one table columns into another table column where id matches Sqlite
You can add a trigger to your python script


CREATE TABLE IF NOT EXISTS sum
        (id TEXT UNIQUE,
    name    TEXT,
    total   TEXT 
    )




CREATE TABLE IF NOT EXISTS newtable
        (id TEXT,
    name    TEXT,
    num TEXT 
    )




INSERT INTO sum(id, name, total) 
    VALUES('001', 'name1', '');




INSERT INTO sum(id, name, total) 
    VALUES('002', 'name2', '');




CREATE TRIGGER sum_after_insert
   AFTER INSERT ON newtable
BEGIN
  UPDATE sum SET total = total + NEW.num WHERE id = NEW.id;
END;




INSERT INTO newtable(id, name, num) 
    VALUES('001', 'name1', '1000');




INSERT INTO newtable(id, name, num) 
    VALUES('002', 'name2', '2000');




INSERT INTO newtable(id, name, num) 
    VALUES('001', 'name1', '4000');




SELECT * FROM sum;


id  | name  | total
:-- | :---- | :----
001 | name1 | 5000 
002 | name2 | 2000 


db&lt;&gt;fiddle here