CREATE TABLE table_17600 ("Rank" FLOAT, "Fastest time  ( s ) " CLOB, "Wind  ( m/s ) " CLOB, "Athlete" CLOB, "Nation" CLOB, "Date" CLOB, "Location" CLOB)

Nigeria competed on July2, 1999.
SELECT "Date" FROM table_17600 WHERE "Nation" = 'Nigeria'
SELECT "Date" FROM "table_17600" WHERE "Nation" = 'Nigeria'