AsGml - geography Data Type
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
SQL database in Microsoft Fabric
Returns the Geography Markup Language (GML) representation of a geography instance.
For more information on Geography Markup Language, see the Open Geospatial Consortium Specification: OGC Specifications, Geography Markup Language.
Syntax
.AsGml ( )
Return Types
SQL Server return type: xml
CLR return type: SqlXml
Remarks
Examples
The following example creates a LineString instance and uses AsGML() to return the GML description of the instance.
DECLARE @g geography;
SET @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326);
SELECT @g.AsGml();
This method returns the description as a LineString instance.
<LineString xmlns="http://www.opengis.net/gml"><posList>47.656 -122.36 47.656 -122.343</posList></LineString>