Table schema:
CREATE TABLE TRANSACTIONS (investor_id VARCHAR); CREATE TABLE INVESTORS (Investor_details VARCHAR, investor_id VARCHAR)

Question: Show the id and details of the investor that has the largest number of transactions.
SQL: SELECT T2.investor_id, T1.Investor_details FROM INVESTORS AS T1 JOIN TRANSACTIONS AS T2 ON T1.investor_id = T2.investor_id GROUP BY T2.investor_id ORDER BY COUNT(*) DESC LIMIT 1