CREATE TABLE table_34940 ("Date" CLOB, "Opponent#" CLOB, "Site" CLOB, "Result" CLOB, "Attendance" CLOB)

What is the Date at memorial stadium minneapolis, mn with an Attendance of 20,000, and a Result of w52-0?
SELECT "Date" FROM table_34940 WHERE "Site" = 'memorial stadium • minneapolis, mn' AND "Attendance" = '20,000' AND "Result" = 'w52-0'
SELECT "Date" FROM "table_34940" WHERE "Attendance" = '20,000' AND "Result" = 'w52-0' AND "Site" = 'memorial stadium • minneapolis, mn'