CREATE TABLE table_50813 ("Edition" CLOB, "Round" CLOB, "Date" CLOB, "Against" CLOB, "Surface" CLOB, "Opponent" CLOB, "Result" CLOB)

what is the date when the surface is clay and the result is 6 7 (4 7) , 1 6?
SELECT "Date" FROM table_50813 WHERE "Surface" = 'clay' AND "Result" = '6–7 (4–7) , 1–6'
SELECT "Date" FROM "table_50813" WHERE "Result" = '6–7 (4–7) , 1–6' AND "Surface" = 'clay'