问如何从多边形表创建多重多边形

EN

DECLARE @gtbl TABLE(g geometry, id INT)
INSERT INTO @gtbl 
SELECT null,1

DECLARE @t TABLE(PK INT Identity(1,1), ISO3 VARCHAR(3))

INSERT INTO @t
Select ISO3 From countries WHERE ISO3 in ('FIN','SWE','NOR','DNK')

Declare @maxPK int; Select @maxPK = MAX(PK) From @t
Declare @pk int; Set @pk = 1

While @pk <= @maxPK

Begin

    IF ((SELECT g FROM @gtbl) IS NULL)
        BEGIN
            UPDATE gtbl SET g = c.Geom.MakeValid()
            FROM @gtbl gtbl, countries c WHERE  c.ISO3 in (Select ISO3 From @T Where PK = @pk)
        END
    ELSE
        BEGIN
            UPDATE gtbl SET g = g.STUnion(c.Geom.MakeValid())
            FROM @gtbl gtbl, countries c
            WHERE  c.ISO3 in (Select ISO3 From @T Where PK = @pk)
        END

    Select @pk = @pk + 1
End


SELECT * FROM @gtbl