SQL Tutorial : DRL / DQL - SELF JOIN

SQL Tutorial : DRL / DQL - SELF JOIN

Let's learn about next topic: SELF JOIN

SELF JOIN:

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EMP     MRG

EID  LNAME     MID EID LNAME    MID

100 A     - 100 A   -

101 B 100  101 B 100

102 C 101  102 C 101

- SELECT E.EMPLOYEE_ID,E.LAST_NAME,M.EMPLOYEE_ID,M.LAST_NAME

FROM EMPLOYEES E,EMPLOYEES M

WHERE E.MANAGER_ID=M.EMPLOYEE_ID

- SELECT E.LAST_NAME,C.LAST_NAME

FROM EMPLOYEES E,EMPLOYEES C

WHERE E.DEPARTMENT_ID=C.DEPARTMENT_ID

AND E.EMPLOYEE_ID <>C.EMPLOYEE_ID AND E.DEPARTMENT_ID =20