Question

I’m developing a search engine for my web project (PHP/MySQL).
User should be able to find a hotel by certain conditions

1. Location
2. Facilities
3. Languages

tables are as following

1. tblHotels *hotel_id* PK hotel_name
2. tblLocations *location_id* PK location_name
3. tblFacilities *facility_id* PK facility_name
4. tblLanguages *language_id* PK language_name
5. tblHotelLocations
   *location_id* FK
   *hotel_id* FK
6. tblHotelFacilities
   *facility_id* FK
   *hotel_id* FK
7. tblHotelLanguages
   *language_id* FK
   *hotel_id* FK

For example user wants to search for hotel, located in San Francisco (*location_id*)
with Free Wi-Fi (*facility_id*) and Pool (*facility_id*)
where staff speaks English (*language_id*) and Spanish (*language_id*)

Obviously, user may change search conditions, like adding Breakfast to facilities or German to languages.
In this case, search results should reflect hotels, where all conditions are true.

Or he may not pick any facilities (languages etc), in this case, only hotels with no facilities at all should be returned.

Is it possible to do it with one query? I’m pretty sure it is and somehow connected with INNER JOINs. But i’m just stuck 🙁 Any clue?

Thanks in advance!

UPDATE: DB Schema attached

/*
-- Query: desc tblHotels
-- Date: 2011-11-02 09:37
*/

INSERT INTO `tblhotels` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('hotel_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tblhotels` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('hotel_name','varchar(45)','YES','UNI',NULL,'');


/*
-- Query: desc tblFacilities
-- Date: 2011-11-02 09:37
*/

INSERT INTO `tblfacilities` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('facility_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tblfacilities` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('facility_name','varchar(45)','YES','UNI',NULL,'');

/*
-- Query: desc tblLocations
-- Date: 2011-11-02 09:37
*/

INSERT INTO `tbllocations` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('location_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tbllocations` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('location_name','varchar(45)','YES','UNI',NULL,'');


/*
-- Query: desc tblLanguages
-- Date: 2011-11-02 09:37
*/

INSERT INTO `tbllanguages` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('language_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tbllanguages` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('language_name','varchar(45)','YES','UNI',NULL,'');


/*
-- Query: desc tblHotelFacilities
-- Date: 2011-11-02 09:39
*/

INSERT INTO `tblhotelfacilities` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('tblHotelFacilities_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tblhotelfacilities` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('facility_id','int(11)','YES','',NULL,'');

INSERT INTO `tblhotelfacilities` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('hotel_id','int(11)','YES','',NULL,'');


/*
-- Query: desc tblHotelLocations
-- Date: 2011-11-02 09:39
*/

INSERT INTO `tblhotellocations` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('tblHotelLocations_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tblhotellocations` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('location_id','int(11)','YES','',NULL,'');

INSERT INTO `tblhotellocations` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('hotel_id','int(11)','YES','',NULL,'');


/*
-- Query: desc tblHotelLanguages
-- Date: 2011-11-02 09:39
*/

INSERT INTO `tblhotelanguages` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('tblHotelLanguages_id','int(11)','NO','PRI',NULL,'auto_increment');

INSERT INTO `tblhotelanguages` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('language_id','int(11)','YES','',NULL,'');

INSERT INTO `tblhotelanguages` (`Field`,`Type`,`Null`,`Key`,`Default`,`Extra`) VALUES ('hotel_id','int(11)','YES','',NULL,'');

Answer 1

Select *
from tbHotels h, tblFacilities f, tblHotelFacilities hf
where f.facilitiesName IN (?,?,?) AND hf.facilityId = f.id 
AND hf.hotelId = h.id

This is a query for only facilities, u can add locations and languages….

?’s can be added like this,

assuming u have an ArrayList containing names of facilities entered by user.

String query = " Select * " +
"from tbHotels h, tblFacilities f, tblHotelFacilities hf"+
"where f.facilitiesName IN <facilities> AND hf.facilityId = f.id "+
"AND f.hotelId = hf.hotelId";

String x = "";
int length = ArrayListOfFacilityNames.length();
while(length>0) {
  x=x+"?, ";
  length = length-1;
}
//remove last "," from string x

x=x.substring(0, x.length -1);

    //paste this string of facilities in main query 

   query = query.replace("<facilities>",x);

   // now ur query contains number of question marks equivalent to number of facilities      entered by user

   //make prepares statement with String query

   Iterator fnames = ArrayListOfFacilitiesNames.Iterator();
   int i=0;
   while(fnames.hasNext())
   {
     String name = fname.next();
     preparesStatement.setString(i,name)
     i++;
   }