MakeValid (geography Data Type)
Converts a geography instance that is not valid into a valid geography instance with a valid Open Geospatial Consortium (OGC) type.
If an input object returns False for STIsValid(), MakeValid() converts the instance that is not valid to a valid instance.
This geography data type method supports FullGlobe instances or spatial instances that are larger than a hemisphere.
Applies to: SQL Server (SQL Server 2012 through current version), Azure SQL Database.
This method may change the type of the geography instance. Additionally, the points of a geography instance may shift slightly. Results from some methods such as NumPoint() may change.
In cases where the invalid spatial instance intersects the equator and has an EnvelopeAngle() = 180, a FullGlobe instance will be returned. The MakeValid() geography data type method will make the best attempt at returning valid instances but the results are not guaranteed to be accurate or precise.
Objects that are not valid can be stored in the database. The methods that can be executed on invalid instances (those instances for which STIsValid() return False) are methods that check validity or allow for export: STIsValid(), MakeValid(), STAsText(), STAsBinary(), ToString(), AsTextZM(), and AsGml().
This method is not precise.
The first example creates an invalid LineString instance that overlaps itself and uses STIsValid() to confirm that it is an invalid instance. STIsValid() returns the value of 0 for an invalid instance.
DECLARE @g geography; SET @g = geography::STGeomFromText('LINESTRING(0 2, 1 1, 1 0, 1 1, 2 2)', 4326); SELECT @g.STIsValid();
The second example uses MakeValid() to make the instance valid and to test that the instance is indeed valid. STIsValid() returns the value of 1 for a valid instance.
SET @g = @g.MakeValid(); SELECT @g.STIsValid();
The third example verifies how the instance has been changed to make it a valid instance.
In this example, when the LineString instance is selected, the values are returned as a valid MultiLineString instance.
MULTILINESTRING ((0 2, 1 1, 2 2), (1 1, 1 0))