sorry to pile on, if you happen to know this,
how can I add a column from another table joined on the username

i.e. change:
SELECT t.username, count(t.username) as TheTotal
FROM Table1 as T

to

SELECT t.username, count(t.username) as TheTotal, p.email
FROM Table1 as T left join Table2 as p on T.username = p.username

This won't work because I get that "p.email is an invalid column name becuase it is not part of an aggregate function or included in the GroupBy clause" error

the rest of the syntax is ok. if i take out "p.email" it executes the query, but of course with no new column