CREATE TABLE table_78967 ("Date" TEXT, "Ship Name" TEXT, "Tonnage" TEXT, "Ship Type" TEXT, "Location" TEXT, "Disposition of Ship" TEXT)

What date was a brig type ship located in SW Approaches?
SELECT "Date" FROM table_78967 WHERE "Ship Type" = 'brig' AND "Location" = 'sw approaches'
SELECT "Date" FROM "table_78967" WHERE "Location" = 'sw approaches' AND "Ship Type" = 'brig'