We're upgrading the loan system and you need to validate repayment posting in UAT. One table has each loan's original principal and current balance; a repayment table records the principal paid each time. A spot check shows Loan A was disbursed at 100,000, has 24,000 of principal repaid, yet the system balance is 78,000. How would you use SQL to find every loan like this?

贷款系统做版本升级，你要在 UAT 验证还款入账逻辑。有一张贷款表，记录每笔贷款的放款本金和当前余额；还有一张还款流水表，记录每次还的本金。抽查发现贷款 A 放款 10 万，累计还本 2.4 万，系统余额却是 7.8 万。你会怎么用 SQL 把所有这类贷款查出来？