Query to get the total effort Projectwise

Question

I have the following table
create table Allocation
  projID varchar(10),
  projName varchar(20),
  associateID number,
  associateName varchar(10),
  allocationStartDate Date,
  allocationEndDate Date,
  allocationPercent number
  PRIMARY KEY(associateID,associateName)
insert into Allocation values ('123','Mr.A','Prj1','Green Computing','to_date('05/15/2011', 'mm/dd//yyyy')','to_date('07/15/2011', 'mm/dd//yyyy')','50');
insert into Allocation values ('123','Mr.A','Prj2','Cloud Computing','to_date('05/31/2011', 'mm/dd//yyyy')','to_date('06/30/2011', 'mm/dd//yyyy')','70');
insert into Allocation values ('1234','Mr.B','Prj1','Green Computing','to_date('06/15/2011', 'mm/dd//yyyy')','to_date('07/31/2011', 'mm/dd//yyyy')','60');
create table Project
  projID varchar(10),
  projName varchar(20),
  StartDate Date,
  EndDate Date,
  PRIMARY KEY(associateName)
insert into Project values ('Prj1','Green Computing','to_date('05/01/2011', 'mm/dd//yyyy')','to_date('07/31/2011', 'mm/dd//yyyy')');
insert into Project values ('Prj2','Cloud Computing','to_date('05/15/2011', 'mm/dd//yyyy')','to_date('08/31/2011', 'mm/dd//yyyy')');I want to select the project wise efforts. i.e. The number of working days multiplied by the 9hrs for each day for all the associates under a project. The result should look something like this
Project ID     Project Name     Associate ID     Associate Name     Effort
Prj1             Green Computing     123                Mr.A            100
Prj1             Green Computing     1234                Mr.B            120Oracle version : 9i 10g/11g

Answer 1

I have made my attempt at mind reading (to correct for errors in script). Do you mean the following:
CREATE TABLE Allocation
   associateID           VARCHAR (10),
   associateName         VARCHAR (100),
   projID                VARCHAR (10),
   projName              VARCHAR (20),
   allocationStartDate   DATE,
   allocationEndDate     DATE,
   allocationPercent     NUMBER,
   CONSTRAINT pk_allocation PRIMARY KEY (associateID, ProjID)
INSERT INTO Allocation
     VALUES ('123',
             'Mr.A',
             'Prj1',
             'Green Computing',
             TO_DATE ('05/15/2011', 'mm/dd/yyyy'),
             TO_DATE ('07/15/2011', 'mm/dd/yyyy'),
             '50');
INSERT INTO Allocation
     VALUES ('123',
             'Mr.A',
             'Prj2',
             'Cloud Computing',
             TO_DATE ('05/31/2011', 'mm/dd/yyyy'),
             TO_DATE ('06/30/2011', 'mm/dd/yyyy'),
             '70');
INSERT INTO Allocation
     VALUES ('1234',
             'Mr.B',
             'Prj1',
             'Green Computing',
             TO_DATE ('06/15/2011', 'mm/dd/yyyy'),
             TO_DATE ('07/31/2011', 'mm/dd/yyyy'),
             '60');
COMMIT;
CREATE TABLE Project
   projID      VARCHAR (10),
   projName    VARCHAR (20),
   StartDate   DATE,
   EndDate     DATE,
   CONSTRAINT pk_project PRIMARY KEY (projID)
INSERT INTO Project
     VALUES ('Prj1',
             'Green Computing',
             TO_DATE ('05/01/2011', 'mm/dd/yyyy'),
             TO_DATE ('07/31/2011', 'mm/dd/yyyy'));
INSERT INTO Project
     VALUES ('Prj2',
             'Cloud Computing',
             TO_DATE ('05/15/2011', 'mm/dd/yyyy'),
             TO_DATE ('08/31/2011', 'mm/dd/yyyy'));
COMMIT;
SELECT a.projid "Project ID",
       p.projname "Project Name",
       a.associateid "Associate ID",
       a.associatename "Associate Name",
       CASE
          WHEN a.allocationenddate - a.allocationstartdate >= 0
          THEN
              /*if project begins and ends on the same day,
                we still want to allocate 9 hrs,
                so we use a "1 + " to account for the first day*/
              to_char((1 + (a.allocationenddate - a.allocationstartdate) * 9))
          WHEN a.allocationenddate is null or a.allocationstartdate is null
          THEN
             /*if project is still underway*/
             'Project is in progress'
          WHEN a.allocationenddate - a.allocationstartdate < 0
          THEN
              /*begin date is later than end date*/
             'Invalid data - begin date must occur before end date'
          ELSE
           null
       END
          "Effort"
  FROM allocation a
  JOIN project p
  ON a.projid = p.projid;