Table: heineken_cup_pool_3
Columns: team
tries_for
tries_against
try_diff
points_for
points_against
points_diff

Question: How many points against has team Cardiff had when there were less than 7 tries?
SQL: SELECT COUNT("points_against") FROM heineken_cup_pool_3 WHERE "team" = 'cardiff' AND "tries_against" < 7