STLineFromText (geography Data Type)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Returns a geography 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
STLineFromText ( 'linestring_tagged_text' , SRID )
Arguments
linestring_tagged_text
Is the WKT representation of the geographyLineString instance you wish to return. linestring_tagged_text is an nvarchar(max) expression.
SRID
Is an int expression representing the spatial reference ID (SRID) of the geographyLineString instance you wish to return.
Return Types
SQL Server return type: geography
CLR return type: SqlGeography
OGC type: LineString
Remarks
This method throws a FormatException if the input is not well-formatted.
Examples
The following example uses STLineFromText() to create a geography instance.
DECLARE @g geography;
SET @g = geography::STLineFromText('LINESTRING(-122.360 47.656, -122.343 47.656 )', 4326);
SELECT @g.ToString();