CREATE TABLE table_78065 ("Theatre" TEXT, "Current show" TEXT, "Classification" TEXT, "Capacity" FLOAT, "Opening date" TEXT, "Closing date" TEXT)

What is the opening date of the musical at the adelphi theatre?
SELECT "Opening date" FROM table_78065 WHERE "Classification" = 'musical' AND "Theatre" = 'adelphi theatre'
SELECT "Opening date" FROM "table_78065" WHERE "Classification" = 'musical' AND "Theatre" = 'adelphi theatre'