CREATE TABLE table_15690 ("Date" TEXT, "Score" TEXT, "Location" TEXT, "Competition" TEXT, "Serial No." TEXT)

A competition of test taking place on 23 Apr 1988 had what as a score?
SELECT "Score" FROM table_15690 WHERE "Competition" = 'test' AND "Date" = '23 apr 1988'
SELECT "Score" FROM "table_15690" WHERE "Competition" = 'test' AND "Date" = '23 apr 1988'