ConvexHullAggregate (geometry Data Type)

**APPLIES TO:** ![yes](media/yes.png)SQL Server (starting with 2012) ![yes](media/yes.png)Azure SQL Database ![no](media/no.png)Azure SQL Data Warehouse ![no](media/no.png)Parallel Data Warehouse

Returns a convex hull for a given set of geometry objects.

Syntax

  
ConvexHullAggregate ( geometry_operand )

Arguments

geometry_operand
Is a geometry type table column that represents a set of geometry objects.

Return Types

SQL Server return type: geometry

Exception

Throws a FormatException when there are input values that are not valid. See STIsValid (geometry Data Type)

Remarks

Method returns null when the input is empty or the input has different SRIDs. See Spatial Reference Identifiers (SRIDs)

Method ignores null inputs.

[!NOTE]
Method returns null if all inputted values are null.

Examples

The following example returns a convex hull of the set of geometry objects in a table variable column.

-- Setup table variable for ConvexHullAggregate example  
DECLARE @Geom TABLE  
(  
shape geometry,  
shapeType nvarchar(50)  
)  
INSERT INTO @Geom(shape,shapeType) VALUES('CURVEPOLYGON(CIRCULARSTRING(2 3, 4 1, 6 3, 4 5, 2 3))', 'Circle'),  
('POLYGON((1 1, 4 1, 4 5, 1 5, 1 1))', 'Rectangle');  
-- Perform ConvexHullAggregate on @Geom.shape column  
SELECT geometry::ConvexHullAggregate(shape).ToString()  
FROM @Geom;