CREATE TABLE table_78427 ("Driver" CLOB, "Constructor" CLOB, "Laps" FLOAT, "Time/Retired" CLOB, "Grid" FLOAT)

How many grids does dave walker have?
SELECT COUNT("Grid") FROM table_78427 WHERE "Driver" = 'dave walker'
SELECT COUNT("Grid") FROM "table_78427" WHERE "Driver" = 'dave walker'