mysql - 谷歌大查询

假设有一个包含两个表的数据库，即Loans和Billpayment。
对于Loans表，我有以下列：

loanId,
clientId(primary key),
DisbursementDate,
applicationDate,
approvalDate,
loanNumber,
loanAmount,
interestRate

Billpayment表列包括：

billId(primary),
customerId(foreign),
billAmount,
payment_status[success/fail],
billDate

我如何才能获得2018年3月已支付账单的客户，并显示在2018年剩余几个月内至少支付了一笔账单的客户数量，除此之外，还要显示账单支付客户在2018年内是否有贷款？

最佳答案

好吧，让我们把这件事做完。我没有测试过这些，也没有对它进行适当的优化，但希望它能有所帮助。
要列出2018年3月的付款，假设我们不在乎是否成功，请执行以下操作：

select * from billpayment
where month(billDate) = 3 and year(billDate) = 2018

若要将相关客户信息包含在上述内容中，请加入：

select * from billpayment
join loans on customerId = clientId
where month(billDate) = 3 and year(billDate) = 2018

若要仅列出在2018年另一个月内也付款的客户，请再次加入派生表：

select * from billpayment b
join loans l on b.customerId = l.clientId
join (select distinct b1.clientId as clientid1 from billpayment b1
      where year(b1.billdate) = 2018 and month(b1.billdate) <> 3) c
        on b.customerId = c.clientId1
where month(b.billDate) = 3 and year(b.billDate) = 2018

要检查他们是否在2018年开始贷款（假设按申请日期），请在where子句中添加and：

select * from billpayment b
join loans l on b.customerId = l.clientId
join (select distinct b1.clientId as clientid1 from billpayment b1
      where year(b1.billdate) = 2018 and month(b1.billdate) <> 3) c
        on b.customerId = c.clientId1
where month(b.billDate) = 3 and year(b.billDate) = 2018
and year(l.applicationDate) = 2018

关于mysql - 谷歌大查询，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/54912789/