CREATE TABLE table_30837 ("By-election" FLOAT, "Electorate" TEXT, "Date" TEXT, "Incumbent" TEXT, "Reason" TEXT, "Winner" TEXT)

When edward shaw is the winner what is the date?
SELECT "Date" FROM table_30837 WHERE "Winner" = 'Edward Shaw'
SELECT "Date" FROM "table_30837" WHERE "Winner" = 'Edward Shaw'