SQLite 3.27

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

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 
    )
CREATE TRIGGER 
AFTER INSERT
ON newtable
FOR EACH ROW
BEGIN
    UPDATE sum 
    SET total = total + NEW.num
    WHERE name = NEW.name;
END
INSERT INTO sum(id, name, total) 
    VALUES('001', 'name1', '')
INSERT INTO sum(id, name, total) 
    VALUES('002', 'name2', '')
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 newtable


id
name
num


001
name1
1000

002
name2
2000

001
name1
4000


SELECT * FROM sum


id
name
total


001
name1
5000

002
name2
2000