Table: west_ham_2008_09_2
Columns: match
date
competition_or_tour
ground
opponent
score1

Question: What match number has a ground of H and the opponent Chelsea under 18s?
SQL: SELECT AVG("match") FROM west_ham_2008_09_2 WHERE "ground" = 'h' AND "opponent" = 'chelsea under 18s'

Question: On what date is there a match lower than 14 with a ground of H and the opponent Aston Villa under 18s?
SQL: SELECT "date" FROM west_ham_2008_09_2 WHERE "match" < 14 AND "ground" = 'h' AND "opponent" = 'aston villa under 18s'

Question: On what date is there a score1 of 2 - 4 with the opponent Chelsea under 18s?
SQL: SELECT "date" FROM west_ham_2008_09_2 WHERE "score1" = '2 - 4' AND "opponent" = 'chelsea under 18s'