joins questions and answer

1. TO DISPLAY ALL THE EMPLOYEE WHO EARN SAME AS SMITH

SELECT A.ENAME,A.SAL,B.ENAME,B.SAL
FROM EMP A,EMP B
WHERE A.SAL=B.SAL
AND A.ENAME='SCOTT'
AND A.EMPNO<>B.EMPNO

2. DISPLAY ALL THE DEPARTMENTAL INFORMATION FOR ALL THE EXISTING EMPLOYEES AND IF A DEPARTMENT HAS NO EMPLOYEES DISPLAY IT AS “NO EMPLOYEES”.
SELECT NVL(ENAME,'NO EMPLOYEE'),DNAME
FROM EMP,DEPT
WHERE EMP.DEPTNO(+)=DEPT.DEPTNO
 
3.SELECT ALL THE EMPLOYEES NAME ALONG WITH THEIR MANAGER NAMES, AND IF AN EMPLOYEE DOES NOT HAVE A MANAGER, DISPLAY HIM AS “CEO”
SELECT A.ENAME EMPLOYEE,NVL(B.ENAME,'CEO') MANAGER
FROM EMP A,EMP B
WHERE A.MGR=B.EMPNO(+)
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