We want to see credit utilization at the time of each transaction. The transaction table has customer, date and amount; the limit-change table records each limit change with its effective date and new limit. Customer 101 had a 10K limit from January 1, raised to 20K on March 15; they spent 5,000 on March 10 and another 5,000 on March 20. How do you match the right limit to each transaction, and what pitfalls worry you most?

我们想看每笔交易发生时客户的额度占用情况。交易表记录客户、日期和金额；额度调整表记录每次调额的生效日期和新额度。客户101一月一日起额度1万，3月15日提到2万；他3月10日和3月20日各刷了5000。你怎么给每笔交易匹配正确的额度？最担心哪些坑？