select userid, name from users group by userid, name is equivalent to select distinct userid, name from users It's easy to add another column to the "distinc

select userid, name from users group by userid, name is equivalent to select distinct userid, name from users It's easy to add another column to the "distinct" based query and change the behavior accidentally. With the "group by" query, you'd get an error saying that the new column needs to be either aggregated or added to the group by.