CREATE TABLE table_19753 ("Result" CLOB, "Date" CLOB, "Race" CLOB, "Venue" CLOB, "Group" CLOB, "Distance" CLOB, "Weight  ( kg ) " CLOB, "Jockey" CLOB, "Winner/2nd" CLOB)

How many different jockeys ran on 17 Feb 2007?
SELECT COUNT("Jockey") FROM table_19753 WHERE "Date" = '17 Feb 2007'
SELECT COUNT("Jockey") FROM "table_19753" WHERE "Date" = '17 Feb 2007'