Conflict creating table with Index and Primary Key - oracle

Question

I'm a veteran SQL Server dev, recently moved to a project requiring Oracle and I'm confused by the error [ORA-02260: table can have only one primary key] I'm getting on Oracle 11.
I'm attempting to create a reference table, with an index and a primary key.
However, getting errors that my column Partner_ID is already declared. I know I'm missing something simple, but the docs and other sources I've viewed here have not given me a clue. Please help me understand what I'm doing wrong.
Thank you
ALTER TABLE REF_PARTNER
DROP PRIMARY KEY CASCADE;
DROP TABLE REF_PARTNER CASCADE CONSTRAINTS;
CREATE TABLE REF_PARTNER
(
PARTNER_ID NUMBER(10) PRIMARY KEY NOT NULL,
GLOBAL_APPID VARCHAR2(256 BYTE) NOT NULL,
FRIENDLY_NAME VARCHAR2(256 BYTE) NOT NULL,
CREATE_DTS DATE,
MODIFIED_DTS DATE,
LAST_MODIFIED_USER VARCHAR2(40 BYTE)
)
TABLESPACE DATA_1
PCTUSED 0
PCTFREE 5
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 1M
NEXT 1M
MAXSIZE UNLIMITED
MINEXTENTS 1
MAXEXTENTS UNLIMITED
PCTINCREASE 0
BUFFER_POOL DEFAULT
)
LOGGING
NOCOMPRESS
NOCACHE
MONITORING;
BEGIN
EXECUTE IMMEDIATE 'DROP SEQUENCE PARTNER_SEQ';
EXCEPTION WHEN OTHERS THEN NULL;
END;
CREATE SEQUENCE PARTNER_SEQ START WITH 1 INCREMENT BY 1 MINVALUE 1 NOMAXVALUE NOCYCLE CACHE 200;
--CREATE UNIQUE INDEX REF_PARTNER_IDX ON REF_PARTNER
--(PARTNER_ID)
--LOGGING
--TABLESPACE INDEX_1
--PCTFREE 10
--INITRANS 2
--MAXTRANS 255
--STORAGE (
-- INITIAL 64K
-- NEXT 64K
-- MAXSIZE UNLIMITED
-- MINEXTENTS 1
-- MAXEXTENTS UNLIMITED
-- PCTINCREASE 0
-- BUFFER_POOL DEFAULT
-- );
--ALTER TABLE REF_PARTNER ADD (
-- CONSTRAINT REF_PARTNER_PK
-- PRIMARY KEY
-- (PARTNER_ID)
-- USING INDEX REF_PARTNER_PK
-- ENABLE VALIDATE);

Answer 1

A assume the error you get is
ORA-01408: such column list already indexed.
This is because you create the table with partner_id as the primary key. This automatically creates a unique index on partner_id.
There is no need to create a unique key on partner_id after you declared it to be the primary key.