Question

我有以下AR查询返回一个房间数组（在给定的时间段内不可用的房间）：

rooms = Room.joins(:bookings).where("(bookings.start_date >= ? AND bookings.start_date <= ?) OR (bookings.end_date >= ? AND bookings.end_date <= ?) OR (bookings.start_date <= ? AND bookings.end_date >= ?)", from, to, from, to, from, to)

我想修改该查询，以便返回所有其他房间;这是在请求的时间段内可用的那些。正确的结果如下：

all_rooms = Room.all
available_rooms = all_rooms - rooms

但我直接想在一个查询中获取可用的房间。我已经添加了一个.not但它没有给我正确的结果：

rooms = Room.joins(:bookings).where.not("(bookings.start_date >= ? AND bookings.start_date <= ?) OR (bookings.end_date >= ? AND bookings.end_date <= ?) OR (bookings.start_date <= ? AND bookings.end_date >= ?)", from, to, from, to, from, to)

我该如何修改查询？

Answer 1

让我们说：

A = (bookings.start_date >= ? AND bookings.start_date <= ?)
B = (bookings.end_date >= ? AND bookings.end_date <= ?) 
C = (bookings.start_date <= ? AND bookings.end_date >= ?)
first_logic  = A or B or C
second_logic = not(first_logic) = not(A or B or C) = not(A) and not(B) and not(C)

available_rooms是second_logic的条件，因此它会像：

available_rooms = Room.joins(:bookings)
                      .where.not("bookings.start_date >= ? AND bookings.start_date <= ?", from, to)
                      .where.not("bookings.end_date >= ? AND bookings.end_date <= ?", from, to)
                      .where.not("bookings.start_date <= ? AND bookings.end_date >= ?", from, to)

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