Get ST_GEOMETRY object's attribute

Question

I have an SDE.ST_GEOMETRY value (Oracle 18c):

select
    sde.st_geometry('LINESTRING EMPTY', 26917) as shape
from
    dual

I want to select one of the ST_GEOMETRY object's attributes:

* Entity
* Numpts
* Minx, miny, maxx, maxy
* Area
* Len
* SRID
* Points

How can I do that with Oracle SQL?

Bud · Answer

For my notes, the result from an object's attribute can be different than the result from the corresponding ST_GEOMETRY function:

Why is (SHAPE).ENTITY different from SDE.ST_ENTITY(SHAPE)?

Bud · Answer

If I understand correctly, SDO_GEOMETRY has similar attributes. Additionally, SDO_GEOMETRY has methods (aka member functions):

* Get_Dims
* Get_GeoJson
* Get_GType
* Get_LRS_Dim
* Get_WKB
* Get_WKT
* ST_CoordDim
* ST_IsValid

Techniques for selecting an object's attribute

Replace value in SDO_ELEM_INFO_ARRAY varray

Modify SDO_ELEM_INFO_ARRAY of existing geometry

Bud · Answer

1. Use dot notation:

select
    sde.st_geometry('LINESTRING EMPTY', 26917).len as shape
from
    dual

If the shape column wasn't already wrapped in brackets via a function, then we would need to add the brackets:

select
    (shape).len
from
    my_fc

2. Or, use a table alias:

select
    a.shape.len
from
    my_fc a

3. Or, use the TREAT() function:

select
    treat(shape as sde.st_geometry).len
from
    my_fc

Although that might be misguided/unnecessary, since wrapping the column in brackets achieves the same thing (brackets is my preferred technique).