CREATE TABLE USER
(
USER_ID VARCHAR2(20 BYTE) NOT NULL,
FNAME VARCHAR2(40 BYTE),
LNAME VARCHAR2(40 BYTE),
EMAIL VARCHAR2(80 BYTE),
CONSTRAINT USER_PK PRIMARY KEY (USER_ID),
)

CREATE TABLE EMP
(
USER_ID VARCHAR2(20 BYTE) NOT NULL,
JOB_TITLE VARCHAR2(40 BYTE),
DEPT_CODE VARCHAR2(10 BYTE),
DEPT_DESC VARCHAR2(40 BYTE),
BIRTH_DATE VARCHAR2(35 BYTE),
MGR_ID VARCHAR2(20 BYTE), 
ACTIVE_FLAG NUMBER(2),
CONSTRAINT EMP_PK PRIMARY KEY (USER_ID),
FOREIGN KEY (USER_ID) 
REFERENCES USER (USER_ID),
)

USER_ID User_Fname User_Lname User_Email Emp_Job_Title Emp_Mgr_id Emp_Mgr_Fname||Lname Active_Flag
1 James Adam Ja@abc.com DA 5 Scott Tiger 1
2 John ding jd@abc.com AC 5 Scott Tiger 1
3 Vince dingo vd@abc.com mgr 4 Jeff marsh 1
4 Jeff Marsh jm@abc.com vp 10 Willi goodman 1
10 Willi Goodman wg@abc.com CEO 1 

select user_id,fname,lname,email,job_title,mgr_id,mgr_id
from User , emp
where  User.user_id = emp.user_id

Select 
 (select lname from user where user_id=x.MGR_ID) lname
from
 (user
  emp join) x