CREATE TABLE table_204_975 (id NUMBER, "year" NUMBER, "competition" CLOB, "location" CLOB, "event" CLOB, "final-rank" CLOB, "final-score" NUMBER, "qualifying rank" NUMBER, "qualifying score" NUMBER)

which competition took place in 2008 but had only one event ?
SELECT "competition" FROM table_204_975 GROUP BY "competition" HAVING COUNT("event") = 1
SELECT "competition" FROM "table_204_975" GROUP BY "competition" HAVING COUNT("event") = 1