sql group by versus distinct

Question

Why would someone use a group by versus distinct when there are no aggregations done in the query?

Also, does someone know the group by versus distinct performance c

Answer 1

In MySQL I've found using a GROUP BY is often better in performance than DISTINCT.

Doing an "EXPLAIN SELECT DISTINCT" shows "Using where; Using temporary " MySQL will create a temporary table.

vs a "EXPLAIN SELECT a,b, c from T1, T2 where T2.A=T1.A GROUP BY a" just shows "Using where"