CREATE TABLE table_11787 ("Home team" CLOB, "Home team score" CLOB, "Away team" CLOB, "Away team score" CLOB, "Venue" CLOB, "Crowd" FLOAT, "Date" CLOB)

On what date was essendon the away team?
SELECT "Date" FROM table_11787 WHERE "Away team" = 'essendon'
SELECT "Date" FROM "table_11787" WHERE "Away team" = 'essendon'