Distributed Database
Applications
COSC 5050
Week One
Outline
Introduction
Course overview
Oracle client environment
Data dictionary
Language fundamentals
Program control
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Introduction
Oracle database
PL/SQL
Accessing Oracle server
Database objects
DDL and DML statements
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PL/SQL
Many Oracle applications are built using
client-server architecture
The Oracle database resides on the server
PL/SQL is like any other programming
language
PL/SQL is not a stand-alone
programming language
PL/SQL is a part of the Oracle RDBMS
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PL/SQL
Highly structured, readable, accessible
language
Standard and portable language
Embedded language
High-performance, highly integrated
database language
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Advantages of PL/SQL
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SQL Example
The semicolon terminates CREATE, INSERT,
SELECT, and DROP statements
CREATE TABLE STUDENT
( FIRST_NAME VARCHAR2(20),
LAST_NAME VARCHAR2(20)
);
INSERT INTO STUDENT VALUES (‘JOHN’, ‘LUCKY’);
SELECT FIRST_NAME, LAST_NAME FROM STUDENT;
DROP TABLE STUDENT;
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PL/SQL Example
Page 7, 8, 9, 39 examples
When Oracle reads a PL/SQL block, a
semicolon marks the end of the
individual statement within the block
It is not a block terminator!
The “/” executes the PL/SQL block
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Integration with SQL
DECLARE
l_book_count INTEGER;
BEGIN
SELECT COUNT(*)
INTO l_book_count
FROM books
WHERE author LIKE '%Feuerstein, Steven%';
DBMS_OUTPUT.PUT_LINE(
'Steven have written (or co-written) ' ||
l_book_count || ' books.');
UPDATE books
SET author = REPLACE (author, 'Steven', 'Stephen')
WHERE author LIKE '%Feuerstein, Steven%';
END;
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Control and Conditional Logic
CREATE OR REPLACE PROCEDURE pay_out_balance(
account_id_in IN accounts.id%TYPE)
IS
l_balance_remaining NUMBER;
BEGIN
LOOP
l_balance_remaining :=
account_balance (account_id_in);
IF l_balance_remaining < 1000
THEN
EXIT;
ELSE
apply_balance (
accont_id_in, l_balance_remaining);
END IF;
END LOOP;
END pay_out_balance;
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When Things Go Wrong
CREATE OR REPLACE PROCEDURE check_account(account_id_in IN accounts.id%TYPE)
IS
l_balance_remaining
NUMBER;
l_balance_below_minimum
EXCEPTION;
l_account_name
accounts.name%TYPE;
BEGIN
SELECT name INTO l_account_name FROM accounts WHERE id = account_id_in;
l_balance_remaining := account_balance (account_id_in);
DBMS_OUTPUT.put_line (
'Balance for ' || l_account_name || ' = ' || l_balance_remaining);
IF l_balance_remaining < 1000
THEN
RAISE l_balance_below_minimum;
END IF;
EXCEPTION
WHEN NO_DATA_FOUND
THEN
log_error (...);
WHEN l_balance_below_minimum
THEN
log_error (...);
RAISE;
END;
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Creating a Stored Program
CREATE OR REPLACE FUNCTION wordcount (str IN VARCHAR2)
RETURN PLS_INTEGER
AS
words PLS_INTEGER := 0;
len PLS_INTEGER := NVL(LENGTH(str),0);
inside_a_word BOOLEAN;
BEGIN
FOR i IN 1..len + 1
LOOP
IF ASCII(SUBSTR(str, i, 1)) < 33 OR i > len
THEN
IF inside_a_word
THEN
words := words + 1;
inside_a_word := FALSE;
END IF;
ELSE
inside_a_word := TRUE;
END IF;
END LOOP;
RETURN words;
END;
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Executing, Showing, and
Dropping a Stored Program
BEGIN
DBMS_OUTPUT.PUT_LINE(
'There are ' || wordcount(CHR(9)) || ' words in a tab');
END;
SELECT * FROM USER_OBJECTS;
DESC wordcount
SELECT TEXT FROM USER_SOURCE WHERE NAME = 'WORDCOUNT';
DROP FUNCTION wordcount;
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Access Oracle
Oracle server (service and host name)
cronus, icarus.acs.webster.edu
Oracle client
Oracle 11g client download
SQL*Plus
SQL Developer
Application Express (APEX) Workspace
Your login and password
Documentations
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Oracle SQL*Plus
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Oracle SQL Developer
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Oracle APEX
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Data Dictionary
USER_
ALL_
DBA_
select view_name from all_views where
view_name like 'USER%';
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Language Fundamentals
PL/SQL block structure
Modularization
Scope
Anonymous blocks
Named blocks
Procedures
Functions
Scope and visibility
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PL/SQL Block Structure
Header
Declaration section
Execution section
Exception section
PROCEDURE get_happy (ename_in IN VARCHAR2)
IS
hiredata DATE;
BEGIN
hiredate := SYSDATE – 2;
INSERT INTO employee (emp_name, hiredate)
VALUES (ename_in, hiredate);
EXCEPTION
WHEN dup_val_in_index
THEN
DBMS_OUTPUT.PUT_LINE (‘Cannot insert.’);
END;
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Anonymous Blocks
No header
Begin with either DECLARE or BEGIN
Cannot be called
BEGIN
DBMS_OUTPUT.PUT_LINE (SYSDATE);
END;
DECLARE
l_right_now DATE := SYSDATE;
BEGIN
DBMS_OUTPUT.PUT_LINE (l_right_now);
END;
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Named Blocks
Procedures
Functions
procedure Add_employee
(ssn
in
varchar2
, fname
in
varchar2
, lname
in
varchar2
, dept_num
in
number
, code
in
number
, sup_ssn
in
varchar2)
is
begin
insert into employee values
(ssn, fname, lname, dept_num, code, sup_ssn);
end; -- Add_employee
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Named Blocks
function get_department(ssn_in in employee.ssn%type)
return department.dept_name%type
is
l_dept_name department.dept_name%type;
begin
select dept_name into l_dept_name
from department inner join employee
on employee.dept_num = department.dept_num
where ssn = ssn_in;
dbms_output.put_line('department name: ' || l_dept_name);
return l_dept_name;
exception
when no_data_found then
dbms_output.put_line(
'no such employee or not in any department!');
return null;
end;
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Named Blocks in DB2
CREATE PROCEDURE sum(
IN p_a INTEGER,
IN p_b INTEGER,
OUT p_s INTEGER)
LANGUAGE SQL
BEGIN
SET p_s = p_a + p_b;
END;
CALL sum(100,200,?);
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Language Fundamentals
PL/SQL character set
Case-insensitive language
Identifiers
Up to 30 characters in length
Must start with a letter
Can include $, _, and #
Cannot contain spaces
PL/SQL keywords
Comments
Single-line comments using “--”
Multi-line comments using /* … */
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PL/SQL Character Set
Type
Characters
Letters
A-Z, a-z
Digits
0-9
Symbols
~!@#$%*()_-+=|:;"'<>,.?/^
Whitespace
Tab, space, newline, carriage return
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Program Control
IF statements
CASE
LOOP
WHILE loop
Cursor loop
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IF Statement
IF salary > 40000
THEN
give_bonus (employee_id, 500);
END IF;
IF salary <= 40000
THEN
give_bonus (employee_id, 0);
ELSE
give_bonus (employee_id, 500);
END IF;
declare
salary number := 40000;
begin
IF salary > 40000
THEN
dbms_output.put_line('Salary is greater than 40000');
ELSE
dbms_output.put_line('Salary is not greater than 40000');
END IF;
end;
/
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IF Statement
declare
salary number := &salary;
begin
IF salary BETWEEN 10000 AND 20000
THEN
dbms_output.put_line('Give bonus 1500.');
ELSIF salary BETWEEN 20000 AND 40000
THEN
dbms_output.put_line('Give bonus 1000.');
ELSIF salary > 40000
THEN
dbms_output.put_line('Give bonus 500.');
ELSE
dbms_output.put_line('Give bonus 0.');
END IF;
end;
/
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CASE Statement
Simple CASE statement
declare
salary_level number := &salary;
begin
case salary_level
when 1 then
dbms_output.put_line('give bonus
when 2 then
dbms_output.put_line('give bonus
when 3 then
dbms_output.put_line('give bonus
else
dbms_output.put_line('give bonus
end case;
end;
/
Distributed Database Applications
1500.');
1000.');
500.');
0.');
Jiangping Wang
CASE Statement
Searched CASE statement
declare
salary number := &salary;
begin
case
when salary between 10000 and 20000 then
dbms_output.put_line('give bonus 1500.');
when salary between 20000 and 40000 then
dbms_output.put_line('give bonus 1000.');
when salary > 40000 then
dbms_output.put_line('give bonus 500.');
else
dbms_output.put_line('give bonus 0.');
end case;
end;
/
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CASE Statement
CASE expression
declare
salary number := &salary;
bonus_amount number;
begin
bonus_amount :=
case
when salary BETWEEN 10000 AND 20000 THEN 1500
when salary BETWEEN 20000 AND 40000 THEN 1000
when salary > 40000 THEN 500
else 0
end;
dbms_output.put_line(
'Give bonus ' || bonus_amount || '.');
end;
/
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Loop Statement
Simple loop
FOR loop
WHILE loop
Cursor FOR loop
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Simple Loop
PROCEDURE set_all_ranks (max_rank_in IN INTEGER)
IS
ranking_level NUMBER (3) := 1;
BEGIN
LOOP
EXIT WHEN ranking_level > max_rank_in;
set_rank (ranking_level);
ranking_level := ranking_level + 1;
END LOOP;
END set_all_ranks;
Use EXIT or EXIT WHEN to exit loop
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For Loop
PROCEDURE set_all_ranks (max_rank_in IN INTEGER)
IS
ranking_level NUMBER (3) := 1;
BEGIN
FOR ranking_level IN 1 .. max_rank_in
LOOP
set_rank (ranking_level);
END LOOP;
END set_all_ranks;
Reverse loop:
FOR counter IN REVERSE 1 .. max
LOOP
…
END LOOP;
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WHILE Loop
PROCEDURE set_all_ranks (max_rank_in IN INTEGER)
IS
ranking_level NUMBER (3) := 1;
BEGIN
WHILE ranking_level <= max_rank_in
LOOP
set_rank (ranking_level);
ranking_level := ranking_level + 1;
END LOOP;
END set_all_ranks;
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Cursor FOR Loop
Cursor with simple loop
DECLARE
CURSOR name_cur IS
SELECT lname, fname
FROM employee WHERE ssn like '8%';
name_rec name_cur%ROWTYPE;
BEGIN
OPEN name_cur;
LOOP
FETCH name_cur INTO name_rec;
EXIT WHEN name_cur%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(
name_rec.fname || ' ' || name_rec.lname);
END LOOP;
CLOSE name_cur;
END;
/
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Cursor FOR Loop
Cursor with simple loop
DECLARE
CURSOR occupancy_cur IS
SELECT pet_id, room_number
FROM occupancy
WHERE occupied_dt = TRUNC(SYSDATE);
occupancy_rec occupancy_cur%ROWTYPE;
BEGIN
OPEN occupancy_cur;
LOOP
FETCH occupancy_cur INTO occupancy_rec;
EXIT WHEN occupancy_cur%NOTFOUND;
update_bill
(occupancy_rec.pet_id, occupancy_rec.room_number);
END LOOP;
CLOSE occupancy_cur;
END;
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Cursor FOR Loop
Cursor For loop
DECLARE
CURSOR occupancy_cur IS
SELECT pet_id, room_number
FROM occupancy
WHERE occupied_dt = TRUNC(SYSDATE);
BEGIN
FOR occupancy_rec IN occupancy_cur
LOOP
update_bill
(occupancy_rec.pet_id, occupancy_rec.room_number);
END LOOP;
END;
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Cursor FOR Loop
Cursor FOR loop
DECLARE
CURSOR name_cur IS
SELECT lname, fname
FROM employee WHERE ssn like '8%';
BEGIN
FOR name_rec IN name_cur
LOOP
DBMS_OUTPUT.PUT_LINE(
name_rec.fname || ' ' || name_rec.lname);
END LOOP;
END;
/
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Homework
Given the table layout, write the SQL to
create the table
Create a script file to load database table
Create an anonymous PL/SQL block to
retrieve data from above database table
Create a simple procedure in your DB2
Company schema to retrieve employee data
Project proposal
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