SQL進行房間可用性

Question

我有以下表結構

客房表

||| room_id ||| name ||| 
||| 1 ||| best ||| 
||| 2 ||| best ||| 
||| 3 ||| best ||| 
||| 4 ||| best ||| 

預訂表

||| room_id ||| date_start ||| date_end  ||| 
||| 1 ||| 2015-01-10 ||| 2015-01-15 ||| 
||| 2 ||| 2015-01-10 ||| 2015-01-18 ||| 
||| 3 ||| 2015-01-05 ||| 2015-01-10 ||| 
||| 4 ||| 2015-01-02 ||| 2015-01-05 ||| 

我想是讓說，如果用戶搜索date_start = 2015-01-10和date_end = 2015-01-14

我想顯示那些日子的空房間。

這是我到目前爲止已經試過

SELECT r.* 
FROM rooms r 
WHERE r.room_id NOT IN (
    SELECT b.room_id FROM bookings b 
    WHERE (b.date_start <= '$data[datestart]' AND b.date_end >= '$data[dateend]')) 

謝謝！

Answer 1

看的可能性：

x/y = your query's "find available for these days" 
a/b = various records' start/end in your db 

這裏的每一種可能的變體：

a b 
---+----+--- 
xy | |  // no overlap 
x | y |  // partial overlap 
x | | y // complete overlap 
    | xy |  // complete overlap 
    | x | y // partial overlap 
    | | xy // no overlap 

一旦緊縮的邏輯下，你最終

(y < a) || (x > b) // no overlap at all 

Answer 2

SELECT rooms.room_id, rooms.name FROM rooms 
INNER JOIN bookings 
ON rooms.room_id =bookings.room_id 
WHERE bookings.date_start >= DATE('2015-01-10') AND bookings.date_end <= DATE('2015-01-14'); 

Answer 3

如果你正在考慮這樣一個日期範圍小號01/10和01/14，有三種情況，其中一個房間不可用：

• 有人有一個起始日期01/10和01/14
• 之間必須有人01/10之間的結束日期和01/14
• 有人在01/10之前的開始日期和01/14之後的結束日期。

因此，對於前兩個，您可以使用BETWEEN運算符來查看日期是否落在該範圍內，並且其他人是否使用大於或小於。

我有什麼建議，是編寫一個查詢來獲取可用客房：

SELECT r.* 
FROM room r 
JOIN bookings b ON b.room_id = r.room_id 
WHERE b.date_start BETWEEN '2015-01-10' AND '2015-01-14' 
    OR b.date_end BETWEEN '2015-01-10' AND '2015-01-14' 
    OR (b.date_start < '2015-01-10' AND b.date_end > '2015-01-14'); 

然後你就可以使用NOT IN從rooms_table的房間不在此禁止列表中選擇：

SELECT r.* 
FROM room r 
WHERE r.room_id NOT IN(
    SELECT r.room_id 
    FROM room r 
    JOIN bookings b ON b.room_id = r.room_id 
    WHERE b.date_start BETWEEN '2015-01-10' AND '2015-01-14' 
    OR b.date_end BETWEEN '2015-01-10' AND '2015-01-14' 
    OR (b.date_start < '2015-01-10' AND b.date_end > '2015-01-14')); 

如果你想避免的子查詢，你可以否定你的每一個條件得到可用客房：

SELECT r.* 
FROM room r 
JOIN bookings b ON b.room_id = r.room_id 
WHERE b.date_start NOT BETWEEN '2015-01-10' AND '2015-01-14' 
    AND b.date_end NOT BETWEEN '2015-01-10' AND '2015-01-14' 
    AND (b.date_start >= '2015-01-10' OR b.date_end <= '2015-01-14'); 

這裏是所有三個例子的SQL Fiddle。