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SQL Server offers unique ways of storing and managing spatial data through the use of its spatial data types and functions. These features enable developers and data analysts to compute and query spatial data directly within their database. Today, we’re going to delve deeper into these data types and see how they can be applied in some familiar SQL Server context.
Spatial Data Types
In SQL server, there are two types of spatial data:
- Geometry data type: It is used to store planar, or flat-earth data. For example, XY coordinates on a city map.
- Geography data type: It is used to store ellipsoidal data, which incorporates a round-earth surface. It’s ideal for larger-scale global coordinates such as GPS.
Now, let’s take a look at some SQL code that uses these spatial data types.
Example: Geometry Data Type
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DECLARE @Shape geometry; SET @Shape = geometry::STGeomFromText('LINESTRING(100 100, 20 20, 30 40, 50 60)', 0); SELECT @Shape.ToString(); |
In this example, we create a LINESTRING object with the geometry data type and select its textual representation.
Example: Geography Data Type
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DECLARE @Location geography; SET @Location = geography::Point(47.65100, -122.34900, 4326); SELECT @Location.ToString(); |
This example creates a Point object using a geography data type and then selects its textual representation.
Spatial Functions
SQL Server provides a set of built-in functions that can be used to manipulate spatial data:
- STArea(): Returns the total area of a geometry instance.
- STDistance(): Returns the shortest distance (in the same unit as the spatial data) between a point in a geography instance and a point in another geography instance.
Example: Using STArea() and STDistance() Spatial Functions
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DECLARE @Shape1 geometry, @Shape2 geometry; SET @Shape1 = geometry::STGeomFromText('POLYGON((1 1, 3 3, 3 1, 1 1))', 0); SET @Shape2 = geometry::STGeomFromText('POINT(2 2)', 0); SELECT @Shape1.STArea() AS Area, @Shape1.STDistance(@Shape2) AS Distance; |
This example uses these spatial functions to calculate the area of a polygon and the distance from the polygon to a point.
Conclusion
Spatial data types and functions can be crucial for managing and manipulating location-based data quickly and easily. By integrating these features into your SQL Server toolbox, you can better analyze your spatial data and gain deeper insights.
Keep exploring, and soon you’ll find even more ways to use spatial functionality in SQL Server!