Mysql 谷歌大查询

假设有一个包含两个表的数据库，即Loans和Billpayment

对于贷款表，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

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如何获取2018年3月已付款的客户，并显示在2018年剩余几个月内至少支付过一次账单的客户的数量，除此之外，还显示账单付款客户是否在2018年内有贷款？

好的，让我们完成这项工作。我没有测试过这些，也没有对其进行适当的优化，但希望它能有所帮助

若要在2018年3月列出付款，假设我们不关心是否成功，请在以下位置执行以下操作：

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

要将相关客户信息包含在上述内容中，请执行加入：

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

要仅列出在2018年下一个月也进行了付款的客户，请再次加入衍生表：

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

若要在申请日期之前检查他们是否在2018年开始贷款，请在您的where条款中添加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

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Loan table的ClientId是billpayment table的CustomerId？这是我的假设，看不出还有什么其他的联系方式。是的..它是@SafiUllah