CREATE USER schemaowner IDENTIFIED BY schemaowner
DEFAULT TABLESPACE users TEMPORARY TABLESPACE temp;
GRANT connect, resource TO schemaowner;

CREATE USER user1 IDENTIFIED BY user1
DEFAULT TABLESPACE users TEMPORARY TABLESPACE temp;
GRANT connect, resource TO user1;

CREATE USER user2 IDENTIFIED BY user2
DEFAULT TABLESPACE users TEMPORARY TABLESPACE temp;
GRANT connect, resource TO user2;

GRANT EXECUTE ON DBMS_RLS TO PUBLIC;

CONN schemaowner/schemaowner@service

CREATE TABLE users 
(id          NUMBER(10)   NOT NULL, 
 ouser       VARCHAR2(30) NOT NULL,
 first_name  VARCHAR2(50) NOT NULL,
 last_name   VARCHAR2(50) NOT NULL);

INSERT INTO users VALUES (1,'USER1','User','One');
INSERT INTO users VALUES (2,'USER2','User','Two');



CREATE TABLE user_data 
(column1     VARCHAR2(50) NOT NULL,
 user_id     NUMBER(10)   NOT NULL,
column 2 VARCHAR2(50));


INSERT INTO user_data (column1, user_id, column2)VALUES (1,'USER1','tester1);
INSERT INTO user_data (column1, user_id, column2)VALUES (2,'USER2','tester2);

user1> select * from schemaowner.user_data;

user_id column1
1           USER1

user1> select * from schemaowner.user_data;

user_id column2  
2          TESTER 2