I have given two examples. Those are self and inner join.
SQL Query on Inner Join
SELECT PROJNO,EMPNO,LASTNAME,DEPTNAME
FROM (TEST.EMP E JOIN
TEST.DEPT DON
D.DEPTNO = E.WORKDEPT) JOIN
TEST.PROJ. P
ON EMPNO = RESPEMP;
The above is the best example for finding match in 3 tables using Inner join.
SQL Query on Self-Join
SELECT A.DEPTNO,A.DEPTNAME,
A.ADMRDEPT,A.DEPTNAMEFROM TEST.DEPT A
TEST.DEPT B
WHERE A.ADMRDEPT =A.DEPTNO;
The above SQL query is the best example for self join.