CREATE TABLE table_75766 ("Date" CLOB, "Tournament" CLOB, "Winning score" CLOB, "Margin of victory" CLOB, "Runner ( s ) -up" CLOB)

Which Date has a Runner(s)-up of bernhard langer, and a Tournament of at&t championship?
SELECT "Date" FROM table_75766 WHERE "Runner(s)-up" = 'bernhard langer' AND "Tournament" = 'at&t championship'
SELECT "Date" FROM "table_75766" WHERE "Runner(s)-up" = 'bernhard langer' AND "Tournament" = 'at&t championship'