CREATE TABLE table_68454 ("Date" CLOB, "Tournament" CLOB, "Surface" CLOB, "Opponent" CLOB, "Score" CLOB)

What was the date of the match against Jean-Julien Rojer, on a clay surface?
SELECT "Date" FROM table_68454 WHERE "Surface" = 'clay' AND "Opponent" = 'jean-julien rojer'
SELECT "Date" FROM "table_68454" WHERE "Opponent" = 'jean-julien rojer' AND "Surface" = 'clay'