when did the transactions that were less that 3000 occur?
select t2.date_of_transaction from sales as t1 join transactions as t2 on t1.sales_transaction_id = t2.transaction_id where t2.amount_of_transaction < 3000
which transactions were sales?
select transaction_id from transactions where transaction_type_code = 'SALE'
ok i see the transactions of the sales. and then what are the ones that were purchases?
select transaction_id from transactions where transaction_type_code = 'PUR'
what investors were involved with those transactions that were under 3000?
select t2.investor_id from sales as t1 join transactions as t2 on t1.sales_transaction_id = t2.transaction_id where t2.amount_of_transaction < 3000