All possible combinations of values

This is a great example, if somewhat simplistic, of when to use a cross join.

select t1.col as t1_col
     , t2.col as t2_col
  from daTable as t1
     , daTable as t2

Here we see the older, "comma list" syntax for a cross join, in which there is no WHERE clause. It is a self join because the table is cross-joined to itself. Notice that in any self-join, we need to use both table aliases and column aliases.

select t1.col as t1_col
     , t2.col as t2_col
  from daTable as t1
cross  
  join daTable as t2

Here we see the newer JOIN syntax for a cross join, in which there is no ON clause. It produces exactly the same results.