Table schema:
CREATE TABLE table_name_37 (competing_entities VARCHAR, sport VARCHAR, age_groups VARCHAR, held_every VARCHAR)

Question: what is the competing entities when the age group is 18 or younger, held every is one year and the sport is table tennis?
SQL: SELECT competing_entities FROM table_name_37 WHERE age_groups = "18 or younger" AND held_every = "one year" AND sport = "table tennis"