= Advanced Topic: Spatial Database with PostGIS =

The advanced topic of our project focuses on integrating the PostGIS extension into PostgreSQL in order to support spatial data processing and location-based queries.

Our implementation extends the existing tourism database by converting latitude and longitude values into geographic points (`GEOGRAPHY(Point,4326)`), enabling efficient distance calculations and proximity searches.

The implementation includes:

 * Installation and configuration of the PostGIS extension.
 * Creation of a geographic column (`geom`) in the `coordinates` table.
 * Population of the spatial column using existing latitude and longitude values.
 * Creation of a GiST spatial index for efficient spatial queries.
 * Implementation of three spatial queries demonstrating practical tourism scenarios:
   * Finding attractions within 5 km of a hotel.
   * Finding the nearest airport for every hotel.
   * Finding the nearest transport station for every hotel.

The complete implementation is provided in the attached files:

 * '''phase5.sql''' – SQL implementation containing the PostGIS setup and all spatial queries.
 * '''phase5.pdf''' – Documentation describing the implementation, design decisions, and explanation of the spatial queries.