What was the purse when the trainer was Aidan O'Brien?
CREATE TABLE table_name_21 (
    purse VARCHAR,
    trainer VARCHAR
)
SELECT purse FROM table_name_21 WHERE trainer = "aidan o'brien"
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 was the purse when the trainer was Aidan O'Brien? ### Input: CREATE TABLE table_name_21 (
    purse VARCHAR,
    trainer VARCHAR
) ### Response: SELECT purse FROM table_name_21 WHERE trainer = "aidan o'brien"