Database Programming

DATABASE
PROGRAMMING
Henry Osborne

DATABASE

A comprehensive collection of
related data organized for
convenient access, generally in a
computer

RELATIONAL DATABASE
A relational database is a collection of data items
organized as a set of formally-described tables from
which data can be accessed or reassembled in
many different ways without having to reorganize the
database tables. The relational database was
invented by E. F. Codd at IBM in 1970.
http://searchsqlserver.techtarget.com/definition/relational-database

INDICES
• Make it possible to organize the data in a table according
to one or more columns.
• One of the cardinal elements of relational databases
• Can usually be created on one or more columns of a table
• Can also be declared as unique
• Primary keys are a special type of unique index that is used
to determine the “natural” method of uniquely identifying a
row in a table

RELATIONSHIPS
• One-to-one: at most, one row in the child table can
correspond to each row in the parent table
• One-to-many: an arbitrary number of rows in the child table
can correspond to any one row in the parent table
• Many-to-many: an arbitrary number of rows in the child
table can correspond to an arbitrary number of rows in the
parent table

DATA TYPES
int or integer
smallint
real
float
char
varchar

Signed integer number, 32 bits in length.
Signed integer number, 16 bits in length.
Signed floating-point number, 32 bits in length.
Signed floating-point number, 64 bits in length.
Fixed-length character string.
Variable-length character string.

CREATING DATABASES
CREATE DATABASE <dbname>;
CREATE SCHEMA <dbname>;

CREATE TABLES
CREATE TABLE <tablename> (
<col1name> <col1type> [<col1attributes>],
[...
<colnname> <colntype> [<colnattributes>]]
);

CREATE TABLES
CREATE TABLE book (
id INT NOT NULL PRIMARY KEY,
isbn VARCHAR(13),
title VARCHAR(255),
author VARCHAR(255),
publisher VARCHAR(255)

);

CREATING INDICES AND
RELATIONSHIPS
CREATE INDEX <indexname>
ON <tablename> (<column1>[, ..., <columnn>]);

CREATE INDEX book_isbn ON book (isbn);

CREATING INDICES AND
RELATIONSHIPS
CREATE TABLE book_chapter (
isbn VARCHAR(13) REFERENCES book (id),
chapter_number INT NOT NULL,
chapter_title VARCHAR(255)

);

DROPPING OBJECTS
DROP TABLE book_chapter;

DROP SCHEMA my_book_database;

ADDING/MANIPULATING DATA
INSERT INTO <tablename> VALUES
(<field1value>[, ..., <fieldnvalue>]);
OR
INSERT INTO <tablename>
(<field1>[, ..., <fieldn>])
VALUES
(<field1value>[, ..., <fieldnvalue>]);

INSERT INTO book (isbn, title, author)
VALUES (’0812550706’, ’Ender’s Game’, ’Orson Scott Card’);

To update records, you can use the UPDATE statement.
UPDATE book
SET publisher = ’Tor Science Fiction’, author = ’Orson S. Card’
WHERE isbn = ’0812550706’;

REMOVE DATA
DELETE FROM book;

DELETE FROM book WHERE isbn = ’0812550706’;

RETRIEVE DATA
SELECT * FROM book;
SELECT * FROM book WHERE author = ’Ray Bradbury’;

SELECT * FROM book
WHERE author = ’Ray Bradbury’ OR author = ’George Orwell’;
SELECT * FROM book
WHERE author = ’Ray Bradbury’ AND publisher LIKE ’%Del Ray’;

SQL JOINS

SELECT *
FROM book INNER JOIN book_chapter
ON book.isbn = book_chapter.isbn;

OUTER JOINS
SELECT book.title, author.last_name
FROM author
LEFT JOIN book ON book.author_id = author.id;

OUTER JOINS
SELECT book.title, author.last_name
FROM author
RIGHT JOIN book ON book.author_id =
author.id;

PHP DATA OBJECTS (PDO)
• The standard distribution of PHP 5.1 and greater includes
PDO and the drivers for SQLite by default
• There are many other database drivers for PDO, including:
• Microsoft SQL Server
• Firebird
• MySQL
• Oracle
• PostgreSQL, and
• ODBC

PHP DATA OBJECTS (PDO)
• Once installed, the process for using each driver is,
for the most part, the same because PDO provides a
unified data access layer to each of these
database engines.
• There is no longer a need for separate mysql_query()
or pg_query() functions.
• PDO provides a single object-oriented interface to
these databases.

DATABASE CONNECTION
$dsn = ’mysql:host=localhost;dbname=library’;
$dbh = new PDO($dsn, ’dbuser’, ’dbpass’);

ERROR HANDLING
try {
$dsn = ’mysql:host=localhost;dbname=library’;
$dbh = new PDO($dsn, ’dbuser’, ’dbpass’);
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, TRUE);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// All other database calls go here

}
catch (PDOException $e)
{
echo ’Failed: ’ . $e->getMessage();
}

DATABASE QUERY WITH PDO
$author = ’’;
if (ctype_alpha($_GET[’author’])){
$author = $_GET[’author’];
}
// Escape the value of $author with quote()
$sql = ’SELECT author.*, book.* FROM author LEFT JOIN book ON author.id =
book.author_id WHERE author.last_name = ’ . $dbh->quote($author);
// Execute the statement and echo the results
$results = $dbh->query($sql);
foreach ($results as $row)

{
echo "{$row[’title’]}, {$row[’last_name’]}n";
}

$results = $dbh->query($sql);
$results->setFetchMode(PDO::FETCH_OBJ);
foreach ($results as $row)
{
echo "{$row->title}, {$row->last_name}n";
}

$sql = "INSERT INTO book (isbn, title, author_id,
publisher_id)
VALUES (’0395974682’, ’The Lord of the Rings’, 1,
3)";
$affected = $dbh->exec($sql);
echo "Records affected: {$affected}";

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