如何从多个表Mysql Php中选择最新记录

Question

我有三个表，我想根据日期时间获取所有表的记录，

这是我的“用户”表

id      name
1       abc
2       xyz

这是我的表“paymentHistory”

id      bookingId           userId          createdOn
1       101                 1               2020-07-10 12:11:14
2       102                 1               2020-07-11 10:31:19 
3       105                 1               2020-07-11 12:31:19 
4       109                 2               2020-07-10 11:45:32 

这是我的表“cancelPaymentHistory”

id      bookingId           userId          createdOn
1       103                 1               2020-07-07 11:31:28
2       100                 1               2020-07-11 11:31:28
3       109                 2               2020-07-08 19:28:41

这是我的桌子“usr_booking”

id      bookingId           userId          status          created_on
1       104                 1               Inprocess       2020-07-07 10:31:28

现在我想根据三个表的 createdOn (DESC) 获取 userId='1' 的所有记录 我该怎么做？

我尝试了以下代码，但显示了很多记录（显示错误的结果）

SELECT u.id as userId,ph.bookingId as paymentHistoryBooking,cph.bookingId as CancelBookingId,ub.bookingId as usrBooking
FROM users u
JOIN paymentHistory ph ON u.id=ph.userId
JOIN cancelPaymentHistory cph ON u.id=cph.id
JOIN usr_booking ub ON u.id=ub.userId
WHERE u.id='152'

Answer 1

您的查询不正确。 首先，您错过了 users 表的别名 u，因此第二行必须如下所示：

FROM users u

第二，在第四行你不小心写了u.id = cph.id，但是你想匹配userId，而不是cancelPaymentHistory.id。此外，您还错过了 cancelPaymentHistory 表的别名。所以正确的第四行必须是这样的：

JOIN cancelPaymentHistory cph ON u.id = cph.userId

整个查询如下所示：

SELECT u.id as userId,ph.bookingId as paymentHistoryBooking,cph.bookingId as CancelBookingId,ub.bookingId as usrBooking 
FROM users u
JOIN paymentHistory ph ON u.id=ph.userId
JOIN cancelPaymentHistory cph ON u.id=cph.userId
JOIN usr_booking ub ON u.id=ub.userId
WHERE u.id='152';

要按所有表格中最新的createdOn 对结果排序，您必须首先确定所有表格中最新的createdOn：

SELECT userId, max(createdOn) as latestActivity
(SELECT userId, max(createdOn) as createdOn
FROM cancelPaymentHistory
UNION
SELECT userId max(createdOn) as createdOn
FROM usr_booking
UNION 
SELECT userId max(createdOn) as createdOn
FROM paymentHistory)

这个结果必须和前面的查询结合起来：

SELECT u.id as userId,ph.bookingId as paymentHistoryBooking,cph.bookingId as CancelBookingId,ub.bookingId as usrBooking 
, max(latestActivity)
FROM users u
JOIN paymentHistory ph ON u.id=ph.userId
JOIN cancelPaymentHistory cph ON u.id=cph.userId
JOIN usr_booking ub ON u.id=ub.userId
JOIN (SELECT userId, max(createdOn) as latestActivity
     FROM (SELECT userId, max(createdOn) as createdOn
     FROM cancelPaymentHistory
     UNION
     SELECT userId, max(created_on) as created_on
     FROM usr_booking
     UNION 
     SELECT userId, max(createdOn) as createdOn
     FROM paymentHistory) a) activity ON activity.userId = u.id
WHERE u.id='1'
ORDER BY activity.latestActivity DESC;

请注意，我仍然在查询中得到ORDER BY。我假设您想为多个用户运行此语句，因此您可以修改 WHERE-Statement 之类的 WHERE u.id IN ('1','2','3') 仍然有一个排序列表。

我已经为你准备好了小提琴http://sqlfiddle.com/#!9/ea835a/28/0