STGeomFromText (geometry Data Type)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Returns a geometry instance from an Open Geospatial Consortium (OGC) Well-Known Text (WKT) representation augmented with any Z (elevation) and M (measure) values carried by the instance.
Syntax
STGeomFromText ( 'geometry_tagged_text' , SRID )
Arguments
geometry_tagged_text
Is the WKT representation of the geometry instance you wish to return. geometry_tagged_text is an nvarchar(max) expression.
SRID
Is an int expression representing the spatial reference ID (SRID) of the geometry instance you wish to return.
Return Types
SQL Server return type: geometry
CLR return type: SqlGeometry
Remarks
The OGC type of the geometry instance returned by STGeomFromText() is set to the corresponding WKT input.
This method will throw a FormatException if the input is not well-formatted.
Examples
The following example uses STGeomFromText() to create a geometry instance.
DECLARE @g geometry;
SET @g = geometry::STGeomFromText('LINESTRING (100 100, 20 180, 180 180)', 0);
SELECT @g.ToString();