Geography Data Type – SQL Server

    Geography data type in SQL Server is a useful tool for storing and manipulating geographic data. It provides a set of functions and tools for working with geographical data, such as points, lines, and polygons. In this blog, we will explore the Geography data type in SQL Server with examples.

Introduction to Geography data type

Geography data type is a built-in data type in SQL Server that is designed to support the storage, manipulation, and analysis of geographic data. It is based on the Open Geospatial Consortium (OGC) Simple Feature Access specification, which provides a standard way to represent geographic data in a database.

The Geography data type in SQL Server stores data in a geographic coordinate system, allowing you to represent points on the surface of the earth using longitude and latitude coordinates. You can also represent lines and polygons by defining a series of points that define the shape of the line or polygon.

Creating a Geography data type in SQL Server

To create a Geography data type in SQL Server, you can use the "geography" keyword and specify the coordinate system you want to use. For example, to create a Geography data type with the WGS 84 coordinate system, you can use the following code:

CREATE TABLE MyGeographyData

(

  ID INT PRIMARY KEY,

  Location GEOGRAPHY

);

 

Inserting data into a Geography data type

To insert data into a Geography data type in SQL Server, you can use the "STGeomFromText" function to convert a string representation of the geographic data into a Geography data type. For example, to insert a point with the longitude -122.33 and latitude 47.61 into a Geography data type, you can use the following code:

INSERT INTO MyGeographyData (ID, Location)

VALUES (1, geography::STGeomFromText('POINT(-122.33 47.61)', 4326));

 

Querying data from a Geography data type

Once you have data stored in a Geography data type, you can use SQL Server's built-in spatial functions to query and manipulate the data. For example, you can use the "STDistance" function to calculate the distance between two points. The following code calculates the distance between the point stored in our MyGeographyData table and the point with the longitude -122.34 and latitude 47.62:

SELECT Location.STDistance(geography::STPointFromText('POINT(-122.34 47.62)', 4326)) AS Distance

FROM MyGeographyData;

 

This will return the distance between the two points in meters.

Conclusion

Geography data type in SQL Server is a powerful tool for working with geographic data. By using the Geography data type and the built-in spatial functions, you can store, manipulate, and analyze geographic data in your database. The examples provided in this blog are just a few examples of how you can use the Geography data type in your SQL Server applications.