Question

How to update value “100” If the $id duplicate by adding +100 to it so the total will be 200 in the level
here is my INSERT statement

  INSERT INTO users (id, name, level) VALUES ($id, 'name', 100 ) 

Answer 1

This should do the trick for you (I am assuming that id is a unique field and can be used to identify the correct row to update):

$query="INSERT INTO 
users (id, name, level) 
VALUES ($id, 'name', 100 ) 
on duplicate key 
    update set level=level+100";