SQL (Structured Query Language)

A standardized computer language called SQL (Structured Query Language) is used to manage, modify, and query data kept in relational databases. SQL is frequently used in GIS (Geographic Information Systems) to extract, sort, and filter both spatial and non-spatial data from spatial databases and attribute tables.

• Selecting particular records from a dataset (such as cities with a population of one million or more) is one of SQL's primary GIS functions.

• Connect tables using shared variables (e.g., connecting district boundaries to population data).

• Modify geometry fields or characteristics.

• Use spatial SQL extensions, such as PostGIS, to execute spatial queries.

Basic SQL Example:

SELECT * FROM parcels WHERE landuse = 'residential';

This command retrieves all parcels where the land use is residential.