1. An Introduction to Oracle
Victor Matos

2. What is ORACLE ?
Very robust implementation of a
Relational Database Management
System (RDBMS)
The relational model of data is simple to understand and has been extensively scrutinized since 1970’s

3. What else is good about ORACLE ?
The company is solid and successful,
since 1994 revenues in the order
of $2+ billion/year
Very popular software,
worldwide distribution
Runs in 100+ different
type of computers

4. Reasons for the Oracle Success
Security Mechanisms users are given specific rights to operate on the data.
Backup and Recovery minimizes data loss and idle time in the presence of failures
Space Management flexible allocation
Open Connectivity uninterrupted services reachable from heterogeneous clients
Development Tools
many to choose from

5. Parts of the Oracle Server
Procedural Option: built-in programming capabilities based on the PL/SQL language
Stored Procedures: programs stored in the server-side could be invoked using an ADA-like interface
Triggers: dormant server-side routines which are ‘fired’ when specific maintenance conditions are met

6. Parts of the Oracle Server cont
Packages: libraries of server-side routines including proc, functions, triggers, user defined data types, constants, variables.

7. Parts of the Oracle Server cont
Distributed Option: data could be stored in different machines and placed in different cities. Oracle Distributed option provides location transparency, the user does not need to be aware of where the data is kept.

8. Oracle Distributed Option

9. Parts of the Oracle Server cont
Parallel Server Option: Independent machines (nodes) which their own memory and disk space could tap into a common disk database. This loosely coupled architecture provides data sharing and message exchange between processes

10. Parallel Server Option

11. Parts of the Oracle Server cont
Parallel Query Option: Computers holding more than one CPU (such as multiPentium Windows NT) could use those processors in solving independent portions of a query. An Oracle control unit breaks the query into pieces, and re-assembles the partial results.

12. Parallel Query Option

13. ORACLE Products SQL * Plus: User-Friendly-Interface, superset of SQL
Oracle-Forms GUI interface (forms, menu, libraries)
Oracle-Reports Multimedia reporting (text, images, charts)
Oracle Loader Migration facilitator, legacy data to Oracle
Developer Integrated development environment:
Designer Forms, Reports, Graphics, Book, Browser,
Procedure builder, SQL*Plus, CASE
Personal Oracle Full version of the Oracle server for the PC

14. ORACLE Architecture Terminology
An instance is a portion of the computers memory and a
collection of processes required by Oracle to operate
A database is the name of a reserved disk area
A tablespace is a collection of datafiles (or tables)
A table is a ‘file’ or container for application-specific data

15. ORACLE Architecture Terminology:
Rollback is the action of setting a data item to its previous
value. For instance, assume an account holds $50, if a
deposit of $1000 on this account is not completed
the balance is set back to $50.
Undo is similar to roll-back, the action of resetting a data
item to its most recent previous value
Dirty-block is a memory resident image of a disk block
which has been changed by a process while in memory
LRU flushes from memory the block which for the longest
period of time has not been used

16. ORACLE Architecture

17. … … ORACLE Architecture A. What is inside of the database dictionary?
SQL> column comments format a35 wrap
SQL> select * from dictionary;
TABLE_NAME COMMENTS
ALL_CATALOG All tables, views, synonyms, and
sequences accessible to the user
ALL_CLUSTERS Description of clusters
accessible to the user
ALL_CONSTRAINTS Constraint definitions on acce
ssible tables
… …
276 rows selected.

18. ORACLE Architecture B. What is inside of a datafile?
SQL> describe user_source
Name Null? Type
NAME NOT NULL VARCHAR2(30)
TYPE VARCHAR2(12)
LINE NOT NULL NUMBER
TEXT VARCHAR2(2000)
NOTE: You could use desc instead of describe

19. ORACLE Architecture

20. ORACLE Architecture 1. CREATE DATABASE Command
Used to create a database, making it available for general use,
with the following options:
o to establish a maximum number of instances, data files,
o redo log files groups, or redo log file members
o to specify names and sizes of data files and redo log files
o to choose a mode of use for the redo log
Warning: This command prepares a database
for initial use and erases any data currently in
the specified files. Only use this command when
you understand its ramifications.

21. ORACLE Architecture CREATE DATABASE Command create database Oracle
controlfile reuse
logfile 'D:\ORAWIN95\DATABASE\log1orcl.ora'
size 200K reuse,
'D:\ORAWIN95\DATABASE\log2orcl.ora'
size 200K reuse
datafile 'D:\ORAWIN95\DATABASE\sys1orcl.ora'
size 20M reuse autoextend on
next 10M maxsize 200M
character set WE8ISO8859P1;

22. ORACLE Architecture CREATE DATABASE Command (details)
CONTROLFILE REUSE reuses existing control files identified by the initialization
parameter CONTROL_FILES
LOGFILE specifies one or more files to be used as redo log files.
MAXLOGFILES specifies the maximum number of redo log file groups that can ever be
created for the database.
MAXLOGMEMBERS specifies the max number of copies, for a redo log file group.
MAXLOGHISTORY specifies the max number of archived redo log files
for automatic media recovery of Oracle7 with the Parallel Server option.
MAXINSTANCES specifies the max number of instances that can simultaneously have
this database mounted and open.

23. ORACLE Architecture CREATE DATABASE Command (details)
ARCHIVELOG In this mode, the contents of a redo log file group must be archived before
the group can be reused.
NOARCHIVELOG In this mode, the contents of a redo log file group need not be archived
before the group can be reused.
CHARACTER SET specifies the character set the database uses to store data.
DATAFILE specifies one or more files to be used as data files. These files all become part
of the SYSTEM tablespace.
AUTOEXTEND enables or disables the automatic extension of a datafile.

24. ORACLE Architecture How to create a TableSpace
CREATE TABLESPACE MyTabspace_2
DATAFILE 'd:\ORAWIN95\DATABASE\MyData2.dat'
SIZE 10M
DEFAULT STORAGE (
INITIAL K
NEXT K
MINEXTENTS 1
MAXEXTENTS 999
PCTINCREASE 10)
ONLINE;
How to eliminate a tablespace
DROP TABLESPACE Mytabspace2
INCLUDING CONTENTS
CASCADE CONSTRAINTS;

25. ORACLE Architecture Create additional tablespaces
-- USER_DATA: “Create user” command sets this as the default tablespace
-- TEMPORARY_DATA: Create user sets this as the temporary tablespace
-- ROLLBACK_DATA: For rollback segments
create tablespace user_data
datafile 'D:\ORAWIN95\DATABASE\usr1orcl.ora' size 3M reuse
autoextend on next 5M maxsize 150M;
create tablespace rollback_data
datafile 'D:\ORAWIN95\DATABASE\rbs1orcl.ora' size 5M reuse
autoextend on next 5M maxsize 150M;
create tablespace temporary_data
datafile 'D:\ORAWIN95\DATABASE\tmp1orcl.ora' size 2M reuse

26. ORACLE Architecture
Rollback_data
User_data
rbs1orcl
usr1orcl
usr2orcl

27. ORACLE Architecture

28. … ORACLE Architecture Creating Rollback Segments
-- Create 16 rollback segments. Allows 16 concurrent users with open
-- transactions updating the database. This should be enough???.
create public rollback segment rb1 storage(initial 50K next 50K)
tablespace rollback_data;
create public rollback segment rb2 storage(initial 50K next 50K) …
create public rollback segment rb16 storage(initial 50K next 50K)

29. ORACLE Architecture

30. (under construction!)
Architecture Summary:
1- tablespace
2- redo log
3- control files
4- user proc
5- server proc
(dbwrt, ckpt, lgwr, smon, pmon, arch, lckn, reco)
6- sga (dict, datacache, redolog, sqlarea)
7- instances

31. SQL * Plus SQL*Plus is a user-friendly-interface imitating
a notepad. Its primary use is in supporting
the construction of simple schema objects.
o Normally used to easily interact with the Oracle server
o Facilitates the prototyping of SQL commands
o ”Quick and dirty” way of developing/testing PL-SQL and
other Oracle objects

32. Using SQL * Plus to create Objects
Schema Objects
users
tables
views
sequences
synonyms
indexes
clusters
hash clusters
Other schema objects such as packages, and triggers will be
discussed later.

33. Using SQL * Plus to create Objects
Create User Command
Creates a database user, or an account through which you can log in to the
database. You can optionally assign the following properties to the user:
default tablespace
temporary tablespace
quotas for allocating space in tablespaces
profile containing resource limits
Example: You can create the user MARIA by issuing the following statement:
CREATE USER Maria
IDENTIFIED BY Macarena
DEFAULT TABLESPACE payroll_ts
QUOTA 10M ON payroll_ts
QUOTA 5M ON temp_ts
QUOTA 5M ON system
PROFILE accountant;
Grant Connect, Resource to Maria;

34. Using SQL * Plus to create Objects
Schema Objects: TABLES
Tables are the basic unit of data storage in an Oracle database.
Data is stored in rows and columns.
Typical datatypes are: CHAR, VARCHAR2, NUMBER, DATE
A row is a collection of column information corresponding to a single record.
You can optionally specify rules for each column of a table. These rules are called integrity constraints. Example: NOT NULL
Once you create a table, you insert rows of data using SQL statements.
Table data can then be queried, deleted, or updated using SQL.

35. Using SQL * Plus to create Objects
Create Table Command
Example I. To define the EMP table owned by SCOTT, you could issue
the following statement:
CREATE TABLE scott.emp (
empno NUMBER CONSTRAINT pk_emp PRIMARY KEY,
ename VARCHAR2(10)
CONSTRAINT nn_ename NOT NULL
CONSTRAINT upper_ename CHECK (ename = UPPER(ename)),
job VARCHAR2(9),
mgr NUMBER
CONSTRAINT fk_mgr REFERENCES scott.emp(empno),
hiredate DATE DEFAULT SYSDATE,
sal NUMBER(10,2) CONSTRAINT ck_sal CHECK (sal > 500),
comm NUMBER(9,0) DEFAULT NULL,
deptno NUMBER(2)
CONSTRAINT nn_deptno NOT NULL
CONSTRAINT fk_deptno REFERENCES scott.dept(deptno) )
PCTFREE 5
PCTUSED 75 ;

36. Using SQL * Plus to create Objects
Create Table Command
Notes
1- This table contains 8 columns. Ex: EMPNO column is of datatype NUMBER and has an
associated integrity constraint named PK_EMP.
2- HIRDEDATE column is of datatype DATE and has a default value of SYSDATE.
3- PCTFREE of 5 indicates that 5% of space is reserved for future updates
4- PCTUSED of 75, says that a minimum of 75% of the table should be used on each data block
5- The constraint on the mgr field indicates that such a value (mgr’s id) must also be found in
the scott.emp table (a recursive reference)

37. Using SQL * Plus to create Objects
Create Table Command. Typical data types

38. Using SQL * Plus to create Objects
Create Table Command.
Example II. Assuming you have the parallel query option, then the fastest method to create a
table that has the same columns as the EMP table, but only for those employees in department 10,
is to issue a command similar to the following:
CREATE TABLE emp_tmp
UNRECOVERABLE
PARALLEL (DEGREE 3) AS
SELECT *
FROM emp
WHERE deptno = 10;
Notes
1- The UNRECOVERABLE keyword speeds up table creation because there is no overhead in
generating and logging redo information.
2- Parallelism speeds up the creation of the table.
3- After the table is created, querying the table is also faster because the same degree of
parallelism is used to access the table.

39. ORACLE: PL/SQL What is PL/SQL ?
PL/SQL stands for Procedural extensions to SQL. It adds programming capabilities to SQL.
It is a block-structured language with a syntax similar to C
Normally used on the server-side, however some client-side products (ORA-FORMS) could also have it as a built-in part.
It is not a stand-alone language

40. PL/SQL Architecture CLIENT SIDE CODE ORACLE SERVER CODE ...
VisualBasic
Java
C, C++
COBOL
MS-Access
PowerSoft
People’s Soft
SAP
HTML + scripts
(JavaScript, Perl, VBS)
...
ORACLE SERVER CODE
PL-SQL (Oracle 7, 8, 8i)
Java (Oracle8i)

41. PL/SQL Architecture

42. PL/SQL Programming PL/SQL = SQL + standard procedural programming
Support for procedures, functions, flow-control statements,
declared variables, user-defined types.
A PL/SQL program is either a procedure, a function, or an
anonymous block
Anonymous blocks are nameless fragments of code normally
executed as script files

43. PL/SQL Programming Block-Structure Declaration Section
Execution Section
Exception Section

44. PL/SQL: Example1
-- CELCIUS1 (Lowest temp, Highest Temp) Converts Fahrenheit temperatures to Celcius. Results are saved
-- into TEMP, a table predefined to hold (number, number, text)
CREATE OR REPLACE
PROCEDURE Celcius1 (Low IN NUMBER, High IN NUMBER) IS
Celcius number;
Fahren number;
Msg varchar2(55);
BEGIN
DELETE FROM temp;
FOR Fahren IN Low..High LOOP
Celcius:= ROUND ( (Fahren -32)*5/9 );
IF (Fahren < 30 ) THEN
Msg := 'Too cold';
ELSIF (Fahren < 70 ) THEN
Msg := 'Cold';
ELSIF (Fahren <80) THEN
Msg := 'Very nice';
ELSE
Msg := 'Hot';
END IF;
INSERT INTO Temp VALUES (Fahren, Celcius, Msg);
END LOOP;
END;
Create table Temp (…)

45. PL/SQL: Example1
Test the program using the following SQL*PLUS commands
SQL> delete from Temp;
SQL> execute Celcius1(0,100);
SQL> select * from temp;
F F F3 ……
Cold
Cold
Very nice
Very nice
Very nice
Very nice
Very nice
Very nice
Very nice
Very nice
Very nice
Very nice
Hot
Hot

46. PL/SQL: Example1
A second way of testing a stored procedures is to call it from an anonymous block. Type in the following code
sql> edit CelciusTest
DECLARE
BEGIN
delete from Temp;
Celcius1 (0,100);
END;
sql> /
sql > select * from Temp;

47. PL/SQL: Example2
The COMPANY database

48. PL/SQL: Example2 -- WorkLoad
-- Employees are either assigned/removed to/from a project
CREATE or REPLACE
PROCEDURE WorkLoad ( p_action VARCHAR2,
p_ssn VARCHAR2,
p_pno NUMBER,
p_hours NUMBER:= 40 ) IS
BEGIN
IF (p_action = 'ASSIGN' ) THEN
INSERT INTO works_on VALUES (p_ssn, p_pno, p_hours);
ELSIF (p_action = 'REMOVE') THEN
DELETE FROM works_on WHERE (essn = p_ssn) AND
(pno = p_pno);
END IF;
END;

49. PL/SQL: Example2 Testing the procedure with an anonymous block.
SQL > edit workLoadTest
DECLARE
BEGIN
WorkLoad('ASSIGN', ,10,1.7);
END;
sql> /
sql> select * from Works_On;

50. PL/SQL Programming
PL/SQL Syntax

51. PL/SQL Programming Defining/Initializing Variables
Salary NUMBER(10,2);
DeptNumber NUMBER := 17;
LastName VARCHAR2(20);
Sex CHAR := ‘F’;
JobType CHAR(15);
TaxDate DATE := ‘15-APR-99’;
Most common data types are:
NUMBER, VARCHAR2, DATE

52. PL/SQL Programming Defining Variables %TYPE Declares a variable with
respect to a Table.Column
Bonus EMP.Sal%TYPE;
EMP
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
7369 SMITH CLERK DEC
7499 ALLEN SALESMAN FEB
7521 WARD SALESMAN FEB
Number(7,2)

53. PL/SQL Programming Defining Variables
%ROWTYPE Defines a record with respect
to an existing table definition
TempEmp EMP%ROWTYPE;
Refers to fields using: TempEmp.Salary
EMP
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
7369 SMITH CLERK DEC
7499 ALLEN SALESMAN FEB
7521 WARD SALESMAN FEB

54. PL/SQL Programming Creating/Debugging a Stored PL/SQL Function
This example shows how to create an debug a PL/SQL stored function using SQL*Plus
CREATE or REPLACE
FUNCTION IsFile ( MyTable IN VARCHAR2 ) RETURN ( boolean ) IS
result user_tables.table_name%TYPE;
BEGIN
SELECT table_name INTO result
FROM user_tables
WHERE table_name = UPPER(MyTable);
RETURN true;
EXCEPTION
WHEN No_Data_Found THEN RETURN false;
END; /
Intentional
error

55. Line and column where error was found
PL/SQL Programming
Creating/Debugging a Stored PL/SQL Function
Warning: Function created with compilation errors.
SQL> show errors
Errors for FUNCTION ISFILE:
LINE/COL ERROR
1/47 PLS-00103: Encountered the symbol "(" when expecting
one of the following:<an identifier>
<a double-quoted delimited-identifier> LONG_ double
SQL> EDIT IsFile.sql
Line and column where error was found
Use the editor to
correct each error in
the script file

56. PL/SQL Programming Creating/Debugging a Stored PL/SQL Function
-- Testing ISFILE( ) function, using an anonymous block
-- Script: isFileTest. Author: V.Matos May 22, 1999.
clear screen
DECLARE
-- put file names here
theFile user_tables.table_name%TYPE := 'EMPXYZ';
BEGIN
delete from temp;
if ISFILE(theFile) then
insert into temp values (1,1, theFile || ' exists');
else
insert into temp values (2,2, theFile || ' does NOT exist');
end if;
END; /
select * from TEMP;
clear buffer -- erase this line and try again

57. PL/SQL Programming Running the anonymous script
Testing the Anonymous Procedure
SQL> @isFileTest
procedure successfully executed
SQL> select * from TEMP;
F1 F2 F3
EMPXYZ does NOT exist
Running the anonymous script
Results are placed into the TEMP table

58. PL/SQL Programming
-- RaiseSalary: Function increases salary of certain employee by PctRaise
CREATE or REPLACE
FUNCTION RaiseSalary ( EmpSsn number,
PctRaise number )
RETURN number IS
NewSalary number;
OldSalary number;
BEGIN
SELECT Salary INTO OldSalary FROM Employee
WHERE SSN = EmpSSN;
NewSalary:= OldSalary * (1 + PctRaise);
UPDATE Employee SET Salary = NewSalary
WHERE SSN = EmpSsn;
RETURN NewSalary;
EXCEPTION
WHEN No_Data_Found THEN
INSERT INTO temp VALUES (EmpSSN, ‘Not found’,Null);
RETURN -1;
END;
Default type is ‘IN’
Returned value

59. PL/SQL Programming -- Anonymous proc. to test the RAISESALARY routine
-- Script: raiseSalaryTest Author: VMatos 20-MAY-99
DECLARE
theSalary EMPLOYEE.SALARY%TYPE;
BEGIN
delete from TEMP;
theSalary := raiseSalary( , 0.10);
insert into TEMP values ( , theSalary, NULL);
END; /
select * from TEMP;
clear buffer /

60. PL/SQL Programming PROCEDURE which returns several results
CREATE or REPLACE
PROCEDURE GetEmpNameSal ( EmpSSN IN number,
EmpName OUT varchar2,
EmpSalary OUT number ) IS
BEGIN
select Lname ||', '|| Fname, Salary
into EmpName, EmpSalary
from Employee
where SSN = EmpSSN;
EXCEPTION
WHEN No_Data_Found THEN
insert into TEMP
values (EmpSSN, ‘ERROR. Emp not found’,NULL);
EmpName:= '***';
EmpSalary:= -1;
END;
OUT variables carry results
outside of the procedure

61. PL/SQL Programming Testing the getEmpNameSal procedure.
-- Script: getEmpNameSalTest
DECLARE
theName TEMP.F3%TYPE;
theSalary EMPLOYEE.SALARY%TYPE;
BEGIN
delete from TEMP;
getEmpNameSal ( , theName, theSalary);
insert into temp
values ( , theSalary, theName);
END; /
F F F3
SMITH, John

62. PL/SQL Programming Anonymous Procedures
The following anonymous procedure performs the following tasks:
Executes stored proc. GetEmpNameSal to obtain the name and salary of the employee whose SSN is Results are saved into the TEMP table.
Invokes the function RaiseSalary to increase the employee’s salary by 10%. Again, a new line is added to TEMP reporting the new salary value.

63. PL/SQL Programming Anonymous Procedures
-- Name: Test2Routines.Sql
-- Anonymous Procedure to Test STORED routines
-- Uses: proc. GetEmpName,and func. RaiseSalary
-- table TEMP (already created with three columns)
DECLARE
EmpName varchar(20);
mSalary number;
BEGIN
DELETE FROM Temp;
GetEmpNameSal ( , EmpName, mSalary);
INSERT INTO Temp VALUES ( , mSalary, EmpName);
mSalary:= RaiseSalary( , 0.10);
END;
Local memory variables defined to
store the Emp name and salary
retrieved using the stored procedure

64. PL/SQL Programming Running the anonymous script
Testing the Anonymous Procedure
SQL> @ Test2Routines
procedure successfully executed
SQL> select * from TEMP;
F F F2
Smith, John
Smith, John
Running the anonymous script
Results are placed into the TEMP table.

65. PL/SQL Programming Invoking a Stored Function from a SQL Query
The numbers in the BASEBALL table are hard to read.
A function BigBucks(...) is called to facilitate the reading of the big numbers in the table
SQL> select * from BASEBALL;
PNAME PSALARY
A. Belle
K. Griffey
B. Bonds
D. Cone
P. Butterfingers

66. PL/SQL Programming
Do this just in case you do not have the BaseBall table!
drop table BASEBALL;
create table BaseBall (Pname varchar2(20),
PSalary varchar2(30));
insert into BaseBall values ('A. Belle', );
insert into BaseBall values ('K. Griffey', );
insert into BaseBall values ('B. Bonds', );
insert into BaseBall values ('D. Cone', );
insert into BaseBall values ('P. Butterfingers', 900);
select * from BaseBall; /

67. PL/SQL Programming Invoking a Stored Function from a SQL Query
-- Playball.sql
-- This is a small SCRIPT (not an anonymous proc.)
-- The pretty function is called from the SQL comnd
column psalary format
column bigbucks(psalary) format a30
select pname, psalary, BigBucks(psalary)
from baseball;
PNAME PSALARY BIGBUCKS(PSALARY)
A. Belle Millions
K. Griffey Billions
B. Bonds Billions
D. Cone Thousands
P. Butterfingers Peanuts

68. PL/SQL Programming A Stored Function for Beautifying Big Numbers
Create or Replace
Function BIGBUCKS ( salary number ) Return varchar IS
Billion number := ;
Million number := ;
Thousand number := ;
Message varchar(30);
Dollars number(6,2);
begin
if (salary >= Billion) then
Dollars:= salary / billion;
message:= LPAD(to_char(dollars),8) || ' Billions';
return (message);
elsif (salary >= Million) then
Dollars:= salary / Million;
message:= LPAD(to_char(dollars),8) || ' Millions';
elsif (salary >= Thousand) then
Dollars:= salary / Thousand;
message:= LPAD(to_char(dollars),8) || ' Thousands';
else
message:= to_char(Salary,'999.00');
message:= LPAD(message,8)||' Peanuts';
end if;
end;
LPAD( ) adds n spaces on
on left side of the string
Numeric format

69. PL/SQL Programming Creating a Store Procedure: A dir-like Routine
1. Type the following code into a text file called: dirStor.sql
create or replace
PROCEDURE dirStor IS
firstcol boolean;
line varchar2(400);
tableName varchar2(20);
columnName varchar2(20);
CURSOR data IS
select table_name, column_name
from user_col_comments;

70. PL/SQL Programming BEGIN delete from dirList; line:= ' ';
tableName:= ' ';
FOR d IN data LOOP
if (tableName <> d.table_name) then
if (line <> ' ') then
line:= line || ');' ;
end if;
insert into dirList values (line);
tableName:= d.table_name;
Line:= UPPER(d.table_name) || ' (' ;
firstcol:= true;
if NOT (firstcol) then
line:= Line || ', ';
firstcol:= false;
line:= line|| LOWER(d.column_Name);
END LOOP;
END;

71. PL/SQL Programming
Type-in the following lines into a file called: dir.sql. Put the file in the directory c:\bin\orawin95
-- Script: dir.sql
execute dirStor
select * from dirList;
NOTE: dirList is a user-created table. You need to make the table before using it. Type the following SQL statement:
CREATE TABLE dirList ( MyTables VARCHAR2(80) );

72. PL/SQL Programming
An example of how to use the dir routine is given below:
PL/SQL procedure successfully completed.
MyTables
DEPARTMENT (dname, dnumber, mgrssn, mgrstartdate);
DEPENDENT (essn, dependent_name, sex, bdate, relationship);
MYLOG (num1, msg);
TEMP (F1, F2, F3);
PROJECT (pname, pnumber, plocation, dnum);
WORKS_ON (essn, pno, hours);
7 rows selected.

73. PL/SQL Programming
Writing a Procedure to (a) Securely Insert Works_On records
(b) Verify Potential Business Rules
The procedure Insert_WorksOn() is invoked to add new records to the Works_On table in a very controlled way. Each call to the function provides the programmers authentication code and data (SSN, ProjNumb, Hour). For example:
Result:= Insert_WorkOn(‘Dilbert’, ,10,40)
If the programmer ‘Dilbert’ is not in the list of peoples authorized to make insertions,
the operation is rejected and MYLOG file is update with a rejection message
If the SSN and PNO provided are already in the Works_On table the current insertion
is rejected and the log file is updated
The function returns a numeric code 1, -1, -2, etc. to indicate the status of the execution.
This number is stored into the variable Result (1: success, negative values: problems).

74. PL/SQL Programming
To execute the examples in this section you may need to do the following DML changes.
create table WORKS_ON (
essn char(9),
pno number,
hours number(5,1),
CONSTRAINT pk_workson_key PRIMARY KEY (essn, pno));
drop table Valid_Operators;
create table VALID_OPERATORS
(Operator_Name varchar2(20) );
insert into VALID_OPERATORS values ('Dilbert');
insert into VALID_OPERATORS values ('Calbert');

75. PL/SQL Programming create or replace
FUNCTION Insert_WorksOn ( Programmer_Id varchar2,
EmployeeSsn number,
ProjectNumber number,
WeeklyHours number )
RETURN number IS
Programmer_Name varchar(20);
Message varchar(70);
BEGIN
-- First block: Is the programmer allowed to insert records?
-- Note: All code goes into one BEGIN...END block.
select Operator_Name into Programmer_Name
from Valid_Operators
where Operator_Name = Programmer_Id;
EXCEPTION
when No_Data_Found then
Insert into Mylog values (Programmer_Id,
'ERROR** unauthorized used of function');
RETURN -1;
END; -- first block

76. PL/SQL Programming -- INSERTWORKSON cont.
-- Second block: Here other conditions could be checked
-- before accepting record into the works_on table
BEGIN
insert into Works_On values
(EmployeeSsn, ProjectNumber, WeeklyHours);
RETURN 1;
EXCEPTION
When DUP_VAL_ON_INDEX then
Message:= ' Emp ' || to_char(EmployeeSsn) ||
' already in proj ' ||
to_char(ProjectNumber);
insert into Mylog values (NULL, Message);
RETURN -2;
When Others then
Message:= ' Emp ' || to_char(EmployeeSsn) ||
' not assigned to ' ||
RETURN -3;
END; -- second block
END;

77. PL/SQL Programming Mylog Employee
--TESTING THE INSERT_WORKSON FUNCTION
DECLARE
theResultCode NUMBER;
BEGIN
delete from mylog;
theResultCode := Insert_WorksOn ('Dilbert', , 10,1.2);
insert into mylog values (' workson 10', theResultCode);
END;
COL COL2
Emp already in proj. 10
workson
ESSN PNO HOURS
Mylog
Employee

78. PL/SQL Programming Result:= Delete_WorkOn(‘Dilbert’,123456789,1)
Writing a Secure Procedure to Delete a Works_On record
The procedure Delete_WorksOn() is invoked to remove records from the
Works_On table. In the function-call the programmers authentication code
and the Works_On key field(s) are supplied. For example: in the following
call, programmer ‘Dilbert’ asks to remove employee from proj. 1.
Result:= Delete_WorkOn(‘Dilbert’, ,1)
If the programmer ‘Dilbert’ is not authorized to make such a deletion, the
operation is rejected and MYLOG file is update with a rejection message
If employee is not in the Works_On table the current deletion is
rejected and the log file is updated otherwise, the record is eliminated
The function returns a numeric code 1, -1, -2, etc. to indicate the status of
the execution. (1: success, negative values: problems).

79. PL/SQL Programming create or replace
FUNCTION Delete_WorksOn ( Programmer_Id varchar2,
EmployeeSsn number,
ProjectNumb number )
RETURN number IS
Programmer_Name varchar(20);
Message varchar(70);
BEGIN
-- First block: Verify that programmer is allowed to delete
-- Note: all code goes in one BEGIN...END block
select Operator_Name into Programmer_Name
from Valid_Operators
where Operator_Name = Programmer_Id;
EXCEPTION
when No_Data_Found then
Message:= 'Programmer not allowed to ' ||
'delete Works_On rec.';
Insert into Mylog values(Programmer_Id, Message );
RETURN -1;
END; -- first block

80. PL/SQL Programming BEGIN delete from Works_On where Essn= EmployeeSsn
-- DELETE_WORKSON script cont.
---Second block: Other conditions could be checked here
-- before deleting the record
BEGIN
delete from Works_On
where Essn= EmployeeSsn
AND
Pno = ProjectNumb;
if (sql%notfound) then
Message:=' ** ' || to_char(EmployeeSsn) ||
' / ' || to_char(ProjectNumb) ||
' not found ';
insert into Mylog values (NULL, Message);
RETURN -2;
end if;
RETURN 1;

81. PL/SQL Programming When Others then
-- DELETE_WORKSON script cont.
---Second block: Other conditions could be checked here
-- before deleting the record
EXCEPTION
When Others then
Message:= ' *** ' || to_char(EmployeeSsn) ||
' remains in Works_On';
insert into Mylog values (NULL, Message);
RETURN -3;
END; -- second block
END;

82. PL/SQL Programming --TESTING THE DELETE_WORKSON FUNCTION
-- DELETE_WORKSON script cont.
---Second block: Other conditions could be checked here
-- before deleting the record
--TESTING THE DELETE_WORKSON FUNCTION
DECLARE
theCode Number;
BEGIN
delete from mylog;
theCode := delete_WorksOn ('Dilbert', , 10);
insert into mylog values ('After delete ', theCode);
END; /
select * from mylog;
select * from works_on where essn like '123%';

83. PL/SQL Programming
Writing a Secure Procedure to Update Project records
The procedure Update_Project( ) is used to modify existing records in the Project table.
Individual records are located using the Pnumber values as search-key. The updating of
projects occurs in the context of a function call such as the example bellow.
The arguments passed to the function are: Programmer_Id, project number, name, location;
and number of responsible department.
Result:= Update_Project(‘Dilbert’,1,‘Cerveza XXX’,‘Margarita’,NULL);
Each project record to be updated must include the project number
More than one field could be updated in a single function call
Project numbers are not changeable (instead delete whole rec. and re-insert with a new number)
If the programmer ‘Dilbert’ is authorized to make deletion, the operation is rejected
If there is no record for project number 1, the current update is rejected
If a field is not going to be updated, the word NULL must be written in the proper column
The function returns a numeric code 1, -1, -2, etc. to indicate the status of the execution.

84. PL/SQL Programming
Writing a Secure Procedure to Update Project records
create or replace
FUNCTION Update_Project( Programmer_Id number,
ProjectNumber number,
ProjectName varchar,
ProjectLocation varchar,
DepartmentNumber number )
RETURN number IS
Programmer_Name varchar2(20);
Message varchar2(70);
VarPnumber number;

85. PL/SQL Programming
Writing a Secure Procedure to Update Project records cont.
BEGIN
-- First block: Is programmer allowed to update projects?
-- NOTE: all code goes in one BEGIN...END block
select Operator_Name into Programmer_Name
from Valid_Operators
where Operator_Name = Programmer_Id;
EXCEPTION
when No_Data_Found then
Message:= 'Programmer not allowed to ' ||
'update Projects';
Insert into Mylog
values (Programmer_Id, Message);
RETURN -1;
END; -- first block

86. PL/SQL Programming
Writing a Secure Procedure to Update Project records cont.
-- Second block: Verify there is a project record matching
-- Pnumber key. If the field is not NULL, modify using given
-- parameter
BEGIN
select Pnumber into VarPnumber from Project
where Pnumber= ProjectNumber;
if (ProjectName is not NULL) then
update Project
set Pname= ProjectName
where Pnumber = ProjectNumber;
end if;
if (ProjectLocation is not NULL) then
set Plocation= ProjectLocation
End if;
if (DepartmentNumber is not NULL) then
set Dnum = DepartmentNumber
RETURN 1 ; -- success !

87. PL/SQL Programming
Writing a Secure Procedure to Update Project records cont.
-- Deal with Update problems here
EXCEPTION
When No_Data_Found then
Message:= ' Project ' ||
to_char(ProjectNumber) ||
' does not exist ';
insert into Mylog values (NULL, Message);
RETURN -2;
When Others then
Message:= ' Project ' ||
to_char(ProjectNumber) ||
' can not be updated ';
RETURN -3;
END; -- second block
END;