drop table workon; drop table employee; drop table project; drop table division;

create table division (did integer, dname varchar (25), managerID integer, constraint division_did_pk primary key (did) );

create table employee (empID integer, name varchar(30), salary float, did integer, constraint employee_empid_pk primary key (empid), constraint employee_did_fk foreign key (did) references division(did) );

create table project (pid integer, pname varchar(25), budget float, did integer, constraint project_pid_pk primary key (pid), constraint project_did_fk foreign key (did) references division(did) );

create table workon (pid integer references project(pid), empID integer references employee(empID), hours integer, constraint workon_pk primary key (pid, empID) );

/* loading the data into the database */

insert into division values (1,'engineering', 2); insert into division values (2,'marketing', 1); insert into division values (3,'human resource', 3); insert into division values (4,'Research and development', 5); insert into division values (5,'accounting', 4);

insert into project values (1, 'DB development', 8000, 2); insert into project values (2, 'network development', 6000, 2); insert into project values (3, 'Web development', 5000, 3); insert into project values (4, 'Wireless development', 5000, 1); insert into project values (5, 'security system', 6000, 4); insert into project values (6, 'system development', 7000, 1);

insert into employee values (1,'kevin', 32000,2); insert into employee values (2,'joan', 42000,1); insert into employee values (3,'brian', 37000,3); insert into employee values (4,'larry', 82000,5); insert into employee values (5,'harry', 92000,4); insert into employee values (6,'peter', 45000,2); insert into employee values (7,'peter', 68000,3); insert into employee values (8,'smith', 39000,4); insert into employee values (9,'chen', 71000,1); insert into employee values (10,'kim', 46000,5); insert into employee values (11,'smith', 46000,1);

insert into workon values (3,1,30); insert into workon values (2,3,40); insert into workon values (5,4,30); insert into workon values (6,6,60); insert into workon values (4,3,70); insert into workon values (2,4,45); insert into workon values (5,3,90); insert into workon values (3,3,100); insert into workon values (6,8,30); insert into workon values (4,4,30); insert into workon values (5,8,30); insert into workon values (6,7,30); insert into workon values (6,9,40); insert into workon values (5,9,50); insert into workon values (4,6,45); insert into workon values (2,7,30); insert into workon values (2,8,30); insert into workon values (2,9,30); insert into workon values (1,9,30); insert into workon values (1,8,30); insert into workon values (1,7,30); insert into workon values (1,5,30); insert into workon values (1,6,30); insert into workon values (2,6,30);

Formulate the following queries: (note, for some queries, you may need to use the combination of join and subqury or correlated subquery, together with group by and having clauses).

Create a view named as EmpInfo that shows the information of each employee and the total number of project he/she participate. Note, for the employee who do not participate any project, the count is 0.

List the name of employee who is working on the project whose budget is below the divisional average project budget (correlated subquery).

List the name of project that some employee(s) who is/are working on it make less than divisional average salary (correlated subquery).

List the total number of division that has 3 or more employees working on projects (correlated subquery).

List the total number of projects accounting division manager works on.

List the name of division that has most of the employees who work on projects. (hint: use having , compare count() to count, use having count (pid) >=ALL (select count (pid) ..)