客房预订管理系统数据库设计

Question

I am developing a DB Design for Conference Meeting Room Booking System.

I am stuck in making Relationship between Rooms & Facilities Entity. There are Facilities (Equipment) like Projector, VoIP, AC etc in each room. How to assign total no. of each equipment per room ?

Example : If I search for Room with 1 VoIP then I should get that Room & If I search for Room with 3 VoIP & 2 AC it will display that room.

Current DB Design

Room ID    Room Name   Facility ID

 1.          R1        11
 2.          R2        14

Facility ID    AC    VoIP    Projector
11.            1      3       1
12.            2      1       0

Please help me to make it better. I want to use join less as much as possible.

Any Help would be appreciated...!!!

Answer 1

I think what you want is a many to one relationship or a "has many". Without typing out your code for you I will give you the basic design concept:

You should have a table for rooms with an id as a primary key(and other relevant details).

For example Rooms:

        id
        roomName
        otherData

Use a second table for facilities. This table should have a primary key id for each individual piece of equipment and then a foreign key called RoomId which will have the value that corresponds to the primary key for the room it is connected with.

Facilities:

         Id
         roomId
         name
         cost
         otherData

Each facilities entry will have its own id, a roomId with will be the same value as the id for the room it belongs to(the id from the rooms table).

This way you can have 5 facilities connected to one room, 4 connected to another, zero connected to another 50 connected to another one etc.

In answer to your follow up question about selecting all rooms with for example 2 VOIP facilities:

     SELECT Count(name) FROM facilities WHERE name = "VOIP" GROUP BY roomID

This query will return a result that counts how many VOIPs are in each room. Now throw this in your WHERE in your query.

   SELECT * FROM room JOIN facilities ON id = roomId
   WHERE (above query) = 2;