SQL Performance and Security

Question

Help needed here please. I am new to this concept and i am working on a tutorial based on SQL performance and security. I have worked my head round this but now i am stuck.
Here is the questions:
1. Analyse possible performance problems, and suggest solutions for each of the following transactions against the database
a) A manager of a project needs to inspect total planned and actual hours spent on a project broken down by activity.
e.g     
Project: xxxxxxxxxxxxxx
Activity Code          planned     actual (to date)
     1          20          25
     2          30          30
     3          40          24
Total               300          200
Note that actual time spent on an activity must be calculated from the WORK UNIT table.
b)On several lists (e.g. list or combo boxes) in the on-line system it is necessary to identify completed, current, or future projects.
2. Security: Justify and implement solutions at the server that meet the following security requirements
(i)Only members of the Corporate Strategy Department (which is an organisation unit) should be able to enter, update and delete data in the project table. All users should be able to read this information.
(ii)Employees should only be able to read information from the project table (excluding the budget) for projects they are assigned to.
(iii)Only the manager of a project should be able to update (insert, update, delete) any non-key information in the project table relating to that project.
Here is the project tables
set echo on
* Changes
* 4.10.00
* manager of employee on a project included in the employee on project table
* activity table now has compound key, based on ID dependence between project
* and activity
drop table org_unit cascade constraints;
drop table project cascade constraints;
drop table employee cascade constraints;
drop table employee_on_project cascade constraints;
drop table employee_on_activity cascade constraints;
drop table activity cascade constraints;
drop table activity_order cascade constraints;
drop table work_unit cascade constraints;
* org_unit
* type - for example in lmu might be FACULTY, or SCHOOL
CREATE TABLE org_unit
ou_id               NUMBER(4)      CONSTRAINT ou_pk PRIMARY KEY,
ou_name          VARCHAR2(40)     CONSTRAINT ou_name_uq UNIQUE
                         CONSTRAINT ou_name_nn NOT NULL,
ou_type          VARCHAR2(30) CONSTRAINT ou_type_nn NOT NULL,
ou_parent_org_id     NUMBER(4)     CONSTRAINT ou_parent_org_unit_fk
                         REFERENCES org_unit
* project
CREATE TABLE project
proj_id          NUMBER(5)     CONSTRAINT project_pk PRIMARY KEY,
proj_name          VARCHAR2(40)     CONSTRAINT proj_name_uq UNIQUE
                         CONSTRAINT proj_name_nn NOT NULL,
proj_budget          NUMBER(8,2)     CONSTRAINT proj_budget_nn NOT NULL,
proj_ou_id          NUMBER(4)     CONSTRAINT proj_ou_fk REFERENCES org_unit,
proj_planned_start_dt     DATE,
proj_planned_finish_dt DATE,
proj_actual_start_dt DATE
* employee
CREATE TABLE employee
emp_id               NUMBER(6)     CONSTRAINT emp_pk PRIMARY KEY,
emp_name          VARCHAR2(40)     CONSTRAINT emp_name_nn NOT NULL,
emp_hiredate          DATE          CONSTRAINT emp_hiredate_nn NOT NULL,
ou_id               NUMBER(4)      CONSTRAINT emp_ou_fk REFERENCES org_unit
* activity
* note each activity is associated with a project
* act_type is the type of the activity, for example ANALYSIS, DESIGN, BUILD,
* USER ACCEPTANCE TESTING ...
* each activity has a people budget , in other words an amount to spend on
* wages
CREATE TABLE activity
act_id               NUMBER(6),
act_proj_id          NUMBER(5)     CONSTRAINT act_proj_fk REFERENCES project
                         CONSTRAINT act_proj_id_nn NOT NULL,
act_name          VARCHAR2(40)     CONSTRAINT act_name_nn NOT NULL,
act_type          VARCHAR2(30)     CONSTRAINT act_type_nn NOT NULL,
act_planned_start_dt     DATE,
act_actual_start_dt      DATE,
act_planned_end_dt     DATE,
act_actual_end_dt     DATE,
act_planned_hours     number(6)     CONSTRAINT act_planned_hours_nn NOT NULL,
act_people_budget     NUMBER(8,2)      CONSTRAINT act_people_budget_nn NOT NULL,
CONSTRAINT act_pk PRIMARY KEY (act_id, act_proj_id)
* employee on project
* when an employee is assigned to a project, an hourly rate is set
* remember that the persons manager depends on the project they are on
* the implication being that the manager needs to be assigned to the project
* before the 'managed'
CREATE TABLE employee_on_project
ep_emp_id          NUMBER(6)     CONSTRAINT ep_emp_fk REFERENCES employee,
ep_proj_id          NUMBER(5)     CONSTRAINT ep_proj_fk REFERENCES project,
ep_hourly_rate      NUMBER(5,2)      CONSTRAINT ep_hourly_rate_nn NOT NULL,
ep_mgr_emp_id          NUMBER(6),
CONSTRAINT ep_pk PRIMARY KEY(ep_emp_id, ep_proj_id),
CONSTRAINT ep_mgr_fk FOREIGN KEY (ep_mgr_emp_id, ep_proj_id) REFERENCES employee_on_project
* employee on activity
* type - for example in lmu might be FACULTY, or SCHOOL
CREATE TABLE employee_on_activity
ea_emp_id          NUMBER(6),
ea_proj_id          NUMBER(5),
ea_act_id          NUMBER(6),      
ea_planned_hours      NUMBER(3)     CONSTRAINT ea_planned_hours_nn NOT NULL,
CONSTRAINT ea_pk PRIMARY KEY(ea_emp_id, ea_proj_id, ea_act_id),
CONSTRAINT ea_act_fk FOREIGN KEY (ea_act_id, ea_proj_id) REFERENCES activity ,
CONSTRAINT ea_ep_fk FOREIGN KEY (ea_emp_id, ea_proj_id) REFERENCES employee_on_project
* activity order
* only need a prior activity. If activity A is followed by activity B then
(B is the prior activity of A)
CREATE TABLE activity_order
ao_act_id          NUMBER(6),      
ao_proj_id          NUMBER(5),
ao_prior_act_id      NUMBER(6),
CONSTRAINT ao_pk PRIMARY KEY (ao_act_id, ao_prior_act_id, ao_proj_id),
CONSTRAINT ao_act_fk FOREIGN KEY (ao_act_id, ao_proj_id) REFERENCES activity (act_id, act_proj_id),
CONSTRAINT ao_prior_act_fk FOREIGN KEY (ao_prior_act_id, ao_proj_id) REFERENCES activity (act_id, act_proj_id)
* work unit
* remember that DATE includes time
CREATE TABLE work_unit
wu_emp_id          NUMBER(5),
wu_act_id          NUMBER(6),
wu_proj_id          NUMBER(5),
wu_start_dt          DATE CONSTRAINT wu_start_dt_nn NOT NULL,
wu_end_dt          DATE CONSTRAINT wu_end_dt_nn NOT NULL,
CONSTRAINT wu_pk PRIMARY KEY (wu_emp_id, wu_proj_id, wu_act_id, wu_start_dt),
CONSTRAINT wu_ea_fk FOREIGN KEY (wu_emp_id, wu_proj_id, wu_act_id)
          REFERENCES employee_on_activity( ea_emp_id, ea_proj_id, ea_act_id)
/* enter data */
start ouins
start empins
start projins
start actins
start aoins
start epins
start eains
start wuins
start pmselect
I have the tables containing ouins and the rest. email me on [email protected] if you want to have a look at the tables.

Answer 1

Answer to your 2nd question is easy. Create database roles for the various groups of people who are allowed to access or perform various DML actions.
The assign the various users to these groups. The users will be restricted to what the roles are restricted to.
Look up roles if you are not familiar with it.