Consider the following schema tables and answer the questions below

CREATE TABLE DEPT (

DEPTNO NUMBER(2) NOT NULL,

DNAME CHAR(14),

LOC CHAR(13),

CONSTRAINT DEPT_PRIMARY_KEY PRIMARY KEY (DEPTNO));

INSERT INTO DEPT VALUES (10,'ACCOUNTING','NEW YORK');

INSERT INTO DEPT VALUES (20,'RESEARCH','DALLAS');

INSERT INTO DEPT VALUES (30,'SALES','CHICAGO');

INSERT INTO DEPT VALUES (40,'OPERATIONS','BOSTON');

CREATE TABLE EMP (

EMPNO NUMBER(4) NOT NULL,

ENAME CHAR(10),

JOB CHAR(9),

MGR NUMBER(4) CONSTRAINT EMP_SELF_KEY

REFERENCES EMP (EMPNO),

HIREDATE DATE,

SAL NUMBER(7,2),

COMM NUMBER(7,2),

DEPTNO NUMBER(2) NOT NULL,

CONSTRAINT EMP_FOREIGN_KEY FOREIGN KEY (DEPTNO) REFERENCES DEPT (DEPTNO),

CONSTRAINT EMP_PRIM_KEY PRIMARY KEY (EMPNO));

INSERT INTO EMP VALUES (7839,'KING','PRESIDENT',NULL,'17-NOV-1981',5000,NULL,10);

INSERT INTO EMP VALUES (7698,'BLAKE','MANAGER',7839,'1-MAY-1981',2850,NULL,30);

INSERT INTO EMP VALUES (7782,'CLARK','MANAGER',7839,'9-JUN-1981',2450,NULL,10);

INSERT INTO EMP VALUES (7566,'JONES','MANAGER',7839,'2-APR-1981',2975,NULL,20);

INSERT INTO EMP VALUES (7654,'MARTIN','SALESMAN',7698,'28-SEP-1981',1250,1400,30);

INSERT INTO EMP VALUES (7499,'ALLEN','SALESMAN',7698,'20-FEB-1981',1600,300,30);

INSERT INTO EMP VALUES (7844,'TURNER','SALESMAN',7698,'8-SEP-1981',1500,0,30);

INSERT INTO EMP VALUES (7900,'JAMES','CLERK',7698,'3-DEC-1981',950,NULL,30);

INSERT INTO EMP VALUES (7521,'WARD','SALESMAN',7698,'22-FEB-1981',1250,500,30);

INSERT INTO EMP VALUES (7902,'FORD','ANALYST',7566,'3-DEC-1981',3000,NULL,20);

INSERT INTO EMP VALUES (7369,'SMITH','CLERK',7902,'17-DEC-1980',800,NULL,20);

INSERT INTO EMP VALUES (7788,'SCOTT','ANALYST',7566,'09-DEC-1982',3000,NULL,20);

INSERT INTO EMP VALUES (7876,'ADAMS','CLERK',7788,'12-JAN-1983',1100,NULL,20);

INSERT INTO EMP VALUES (7934,'MILLER','CLERK',7782,'23-JAN-1982',1300,NULL,10);

CREATE TABLE SALGRADE (

GRADE NUMBER,

LOSAL NUMBER,

HISAL NUMBER);

INSERT INTO SALGRADE VALUES (1,700,1200);

INSERT INTO SALGRADE VALUES (2,1201,1400);

INSERT INTO SALGRADE VALUES (3,1401,2000);

INSERT INTO SALGRADE VALUES (4,2001,3000);

INSERT INTO SALGRADE VALUES (5,3001,9999);

Question 1: 1. Write a query to display deptno, dname and count of CLERKS in each department. 2. Write a query to show empno, ename, managers name and managers deptno in a report form. Question 2: Write a query that shows all employees making more than average salary. Question 3: Write a query to list the length of service of the employees using the number of days. 

Question 4: Show the number of employees in each salary grade. Question 5: Write a query to show ename, sal and comm and salgrade (based on sal and comm combined). Question 6: Write a query that shows all managers that do not have any employees.