PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual117 / 310ExamplesSELECT ST_Y(ST_GeomFromEWKT(’POINT(1 2 3 4)’));st_y------2(1 row)SELECT ST_Y(ST_Centroid(ST_GeomFromEWKT(’LINESTRING(1 2 3 4, 1 1 1 1)’)));st_y------1.5(1 row)See AlsoST_Centroid, ST_GeomFromEWKT, ST_M, ST_X, ST_YMax, ST_YMin, ST_Z7.4.31 ST_ZST_Z — Return the Z coordinate of the point, or NULL if not available. Input must be a point.Synopsisfloat ST_Z(geometry a_point);DescriptionReturn the Z coordinate of the point, or NULL if not available. Input must be a point.This method implements the SQL/MM specification.This function supports 3d and will not drop the z-index.ExamplesSELECT ST_Z(ST_GeomFromEWKT(’POINT(1 2 3 4)’));st_z------3(1 row)See AlsoST_GeomFromEWKT, ST_M, ST_X, ST_Y, ST_ZMax, ST_ZMin7.4.32 ST_ZmflagST_Zmflag — Returns ZM (dimension semantic) flag of the geometries as a small int. Values are: 0=2d, 1=3dm, 2=3dz, 3=4d.