SELECT avg(amount_of_transaction) FROM TRANSACTIONS WHERE transaction_type_code  =  "SALE"
Show the average amount of transactions with type code "SALE".
SELECT avg ( amount_of_transaction ) FROM TRANSACTIONS WHERE transaction_type_code = `` SALE ''
select avg ( amount_of_transaction ) from transactions where transaction_type_code = value
Show the average amount of transactions with type code `` SALE '' .