Which Date has a Runner(s)-up of bernhard langer, and a Tournament of at&t championship?
CREATE TABLE table_75766 (
    "Date" text,
    "Tournament" text,
    "Winning score" text,
    "Margin of victory" text,
    "Runner(s)-up" text
)
SELECT "Date" FROM table_75766 WHERE "Runner(s)-up" = 'bernhard langer' AND "Tournament" = 'at&t championship'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Which Date has a Runner(s)-up of bernhard langer, and a Tournament of at&t championship? ### Input: CREATE TABLE table_75766 (
    "Date" text,
    "Tournament" text,
    "Winning score" text,
    "Margin of victory" text,
    "Runner(s)-up" text
) ### Response: SELECT "Date" FROM table_75766 WHERE "Runner(s)-up" = 'bernhard langer' AND "Tournament" = 'at&t championship'