How to create a view - oracle

Question

I was trying to create a view with information of latest hired employee in each branch. But i was not succeed in that. Can anyone direct me towards the right path.
CREATE TABLE BRANCH(
BRANCH_ID NUMBER(8) PRIMARY KEY,
BRANCH_NAME VARCHAR2(100) NOT NULL,
SCHEDULE_LINK_NUM NUMBER(8),
MAIN_BRANCH_ID number(8),
BRANCH_MGR_ID NUMBER(8),
BRANCH_OPEN_DATE DATE,
EMAIL VARCHAR2(50),
URL VARCHAR2(50)
);
CREATE TABLE EMPLOYEE(
EMPLOYEE_ID NUMBER(8) PRIMARY KEY,
FIRST_NAME VARCHAR2(50),
LAST_NAME VARCHAR2(50),
MIDDLE_NAME VARCHAR2(50),
GENDER CHAR(1),
SSN NUMBER(9) NOT NULL,
DOB DATE,
MARITAL_STATUS VARCHAR2(30),
SPOUSE_NAME VARCHAR2(50),
HOME_PHONE NUMBER(10),
CELL_PHONE NUMBER(10),
OFFICE_PH_EXTN NUMBER(6),
EMPLOYEE_TYPE VARCHAR2(40),
SALARY NUMBER(10,2),
TAX_DEDUCTION NUMBER(10,2),
BRANCH_ID NUMBER(8),
MGR_ID NUMBER(8),
CONSTRAINT EMP_BRANCH_FKEY FOREIGN KEY(BRANCH_ID) REFERENCES BRANCH(BRANCH_ID),
CONSTRAINT EMP_EMPTYPE_CHECK CHECK(EMPLOYEE_TYPE IN ('MANAGER', 'MECHANIC', 'SECRETARY', 'SALES PERSON')),
CONSTRAINT EMP_MARITSTATUS_CHECK CHECK(MARITAL_STATUS IN ('SINGLE', 'MARRIED', 'DIVORCED'))
);
CREATE TABLE EMP_WORK_HISTORY(
BRANCH_EMP_NUM NUMBER(8) PRIMARY KEY,
BRANCH_ID NUMBER(8),
EMPLOYEE_ID NUMBER(8),
JOIN_DATE DATE NOT NULL,
RELIEVING_DATE DATE,
EMPLOYEE_TYPE VARCHAR2(40),
DESCRIPTION VARCHAR2(200),
CONSTRAINT BRANCH_WRKHIS_BID_FKEY FOREIGN KEY(BRANCH_ID) REFERENCES BRANCH(BRANCH_ID),
CONSTRAINT BRANCH_WRKHIS_EID_FKEY FOREIGN KEY(EMPLOYEE_ID) REFERENCES EMPLOYEE(EMPLOYEE_ID),
CONSTRAINT EMP_WRKHIS_EMPTYPE_CHECK CHECK(EMPLOYEE_TYPE IN ('MANAGER', 'MECHANIC', 'SECRETARY', 'SALES PERSON'))
);
I have written the view like below:
CREATE VIEW LAST_EMPLOYEE_BRANCH AS
WITH LAST_EMP_BRANCH AS
(SELECT MAX(EWH.JOIN_DATE) AS LAST_HIRED_DATE, EWH.BRANCH_ID
FROM EMP_WORK_HISTORY EWH GROUP BY EWH.BRANCH_ID)
SELECT E.FIRST_NAME || E.LAST_NAME AS EMPLOYEE_NAME,
B.BRANCH_NAME, LEB.LAST_HIRED_DATE, E.SALARY,
EXTRACT(YEAR FROM NUMTOYMINTERVAL(MONTHS_BETWEEN(TRUNC(SYSDATE),E.DOB),'MONTH')) AS AGE
FROM EMPLOYEE E, BRANCH B, LAST_EMP_BRANCH LEB
WHERE E.BRANCH_ID = B.BRANCH_ID
AND LEB.BRANCH_ID = E.BRANCH_ID;
By running the above view i am getting all employees records. Can anyone help on this?

Answer 1

Looks like you forgot to include the EMP_WORK_HISTORY table and the LAST_HIRED_DATE column in the join. Try the query below:
CREATE OR REPLACE VIEW LAST_EMPLOYEE_BRANCH AS
WITH LAST_EMP_BRANCH AS
(SELECT MAX(EWH.JOIN_DATE) AS LAST_HIRED_DATE, EWH.BRANCH_ID
FROM EMP_WORK_HISTORY EWH GROUP BY EWH.BRANCH_ID)
SELECT E.FIRST_NAME || E.LAST_NAME AS EMPLOYEE_NAME,
B.BRANCH_NAME, LEB.LAST_HIRED_DATE, E.SALARY,
EXTRACT(YEAR FROM NUMTOYMINTERVAL(MONTHS_BETWEEN(TRUNC(SYSDATE),E.DOB),'MONTH')) AS AGE
FROM EMPLOYEE E, BRANCH B, LAST_EMP_BRANCH LEB, EMP_WORK_HISTORY EWH
WHERE E.BRANCH_ID = B.BRANCH_ID
AND LEB.BRANCH_ID = E.BRANCH_ID
AND E.EMPLOYEE_ID = EWH.EMPLOYEE_ID
AND B.BRANCH_ID = EWH.BRANCH_ID
AND LEB.LAST_HIRED_DATE = EWH.JOIN_DATE;