I think you have wrongly entered the SRID as 4326. In Oracle EPSG:4326 is equivalent to SRID:8307.

Try the following oracle SQL to create table, enter its details in METADATA and index it.

--Create table

CREATE TABLE country_list (sl_no NUMBER PRIMARY KEY, country VARCHAR2(50), boundary sdo_geometry);

--Insert into METADATA

INSERT INTO user_sdo_geom_metadata VALUES ('country_list', 'boundary', SDO_DIM_ARRAY (SDO_DIM_ELEMENT('Long', -180, 180, 0.00001), SDO_DIM_ELEMENT('Lat', -90, 90, 0.00001)), 8307);

--Create index

CREATE INDEX country_list_SIDX on country_list (boundary) indextype is MDSYS.SPATIAL_INDEX;

If still you are not able to see the layer, give a try to Oracle Mapbuilder to see the preview of the loaded polygons. You need registration for downloading this mapbuilder.

If the mapbuilder shows the preview then the problem is with ArcMap not with Oracle.

All the best!!

I think you have wrongly entered the SRID as 4326. In Oracle EPSG:4326 is equivalent to SRID:8307.

Try the following oracle SQL to create table, enter its details in METADATA and index it.

--Create table

CREATE TABLE country_list (sl_no NUMBER PRIMARY KEY, country VARCHAR2(50), boundary sdo_geometry);

--Insert into METADATA

INSERT INTO user_sdo_geom_metadata VALUES ('country_list', 'boundary', SDO_DIM_ARRAY (SDO_DIM_ELEMENT('Long', -180, 180, 0.00001), SDO_DIM_ELEMENT('Lat',   -90,  90, 0.00001)), 8307);

--Create index

CREATE INDEX country_list_SIDX on country_list (boundary) indextype is MDSYS.SPATIAL_INDEX;

If still you are not able to see the layer, give a try to Oracle Mapbuilder to see the preview of the loaded polygons. You need registration for downloading this mapbuilder.

If the mapbuilder shows the preview then the problem is with ArcMap not with Oracle.