What shows for Tie no when Sheffield United was the Away team?
CREATE TABLE table_42787 (
    "Tie no" text,
    "Home team" text,
    "Score" text,
    "Away team" text,
    "Attendance" text
)
SELECT "Tie no" FROM table_42787 WHERE "Away team" = 'sheffield united'
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: What shows for Tie no when Sheffield United was the Away team? ### Input: CREATE TABLE table_42787 (
    "Tie no" text,
    "Home team" text,
    "Score" text,
    "Away team" text,
    "Attendance" text
) ### Response: SELECT "Tie no" FROM table_42787 WHERE "Away team" = 'sheffield united'