When william b. campbell (u) is the successor what is the district?
CREATE TABLE table_2147588_4 (
    district VARCHAR,
    successor VARCHAR
)
SELECT district FROM table_2147588_4 WHERE successor = "William B. Campbell (U)"
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: When william b. campbell (u) is the successor what is the district? ### Input: CREATE TABLE table_2147588_4 (
    district VARCHAR,
    successor VARCHAR
) ### Response: SELECT district FROM table_2147588_4 WHERE successor = "William B. Campbell (U)"