Database Basics and MySQL

Creation, Manipulation, and Management

Jerome Locson
Developer, Ariba Tech Solutions
me@jeromelocson.com

 Graduate from ADZU, BSCS
 PhilNITS FE Passer
 GTUG PH, Zamboanga Chapter Community
Manager
 Technopreneur, Ariba Tech Solutions
 Blog: www.jeromelocson.com

 Relational Database Concept
 Structure Query Language (SQL)
◦ DDL, DML and DCL
 Database Normalization
 ACID Property
 Relational Database Management Systems
(RDBMS), MySQL
 Example of MySQL Queries (PhpMyAdmin)
 SQL Injection Prevention

◦ Used by all major commercial database systems
◦ Very simple model
◦ Query with high-level languages: simple yet
expressive
◦ Efficient implementations

Schema = structural description of relations in database
Instance = actual contents at given point in time

Database = set of named relations (or tables)
Each relation has a set of named attributes (or
columns)
Each tuple (or row) has a value for each attribute
Each attribute has a type (or domain)

NULL – special value for “unknown” or “undefined”

Key – attribute whose value is unique in each tuple
Or set of attributes whose combined values are
unique

 Standard/dominant language for accessing
databases and processing
 Steady improvements in reliability,
performance and security
 Applicable to many database systems

 It can define a database (DDL)
 It can manipulate database (DML)
 and, can control a database (DCL)

 defining the structure and contents of a
relational database
 Metadata (data about the data)
 defines the mapping of database to physical
hardware and devices
 Basic Syntax:
◦ Create Table, Alter Table, Drop Table, Create View,
Create User, etc.

 specifies how queries and updates are to be
done
 Basic Syntax:
◦ Select, Insert, Delete, Update

 involves configuring and controlling the
database - permission, roles, and referential
integrity
 Basic Syntax:
◦ Grant, Check, Constraint, Primary Key, Foreign Key

 Process of efficiently organizing data in a
database (1NF-5NF)
 Too: Entity-Relationship Diagram (ERD)
 Goals:
◦ eliminating redundant data
◦ ensuring data dependencies make sense
 Forms:
◦ 1NF (First Normal Form)
◦ 2NF (Second Normal Form)
◦ 3NF (Third Normal Form)

 First normal form (1NF) sets the very basic
rules for an organized database:

◦ Eliminate duplicative columns from the same table.
◦ Create separate tables for each group of related
data and identify each row with a unique column or
set of columns (the primary key).

 Second normal form (2NF) further addresses
the concept of removing duplicative data:

◦ Meet all the requirements of the first normal form.
◦ Remove subsets of data that apply to multiple rows
of a table and place them in separate tables.
◦ Create relationships between these new tables and
their predecessors through the use of foreign keys.

 Third normal form (3NF) goes one large step
further:
◦ Meet all the requirements of the second normal
form.
◦ Remove columns that are not dependent upon the
primary key.

 Stands for atomicity, consistency, isolation,
durability
 set of properties that guarantee database
transactions are processed reliably

 Atomicity (atomic)
◦ requires that database modifications must follow an
"all or nothing" rule
◦ If one part of the transaction fails, the entire
transaction fails and the database state is left
unchanged.

 Consistency
◦ ensures that any transaction the database performs
will take it from one consistent state to another
◦ only consistent (valid according to all the rules
defined) data will be written to the database
◦ whatever rows will be affected by the transaction
will remain consistent with each and every rule

 Isolation
◦ no transaction should be able to interfere with
another transaction at all
◦ use a serial model where no two transactions can
occur on the same data at the same time

 Durability
◦ once a transaction has been committed, it will
remain so
◦ every committed transaction is protected against
power loss/crash/errors and cannot be lost by the
system and can thus be guaranteed to be
completed

 RDBMS is the basis for SQL, and for all
modern database systems like MS SQL Server,
IBM DB2, Oracle, MySQL, and Microsoft
Access.
 MySQL database is the world's most popular
open source database for the Web
 Supports different languages,
environment, etc.
 www.mysql.com

• mysql_connect(host, username
[,password]);
◦ Connects to a MySQL server on the specified host
using the given username and/or password.
Returns a MySQL link identifier on success, or FALSE
on failure.
• mysql_select_db(db_name [,resource])
◦ Selects a database from the database server.

• mysql_query(SQL, resource);
◦ Sends the specified SQL query to the database
specified by the resource identifier. The retrieved data
are returned by the function as a MySQL result set.
• mysql_result(result, row [,field]);
◦ Returns the contents of one cell from a MySQL result
set. The field argument can be the field name or the
field’s offset.
• mysql_fetch_array(result [,result_type])
◦ Fetch a result row as an associative array, a numeric
array, or both. The result type can take the constants
MYSQL_ASSOC, MYSQL_NUM, and MYSQL_BOTH.

• mysql_free_result(result)
◦ Frees the result set
• mysql_close(resource)
◦ Closes the connection to the database.

 If there is error in the database connection,
you can terminate the current script by
using the die function.
 For example:
$db = mysql_connect("localhost", "root“, “”)
or die("Could not connect : " .
mysql_error());

mysql_select_db("my_database")
or die("Could not select database");

$result = mysql_query($query)
or die("Query failed");

<?php
/* Connecting, selecting database */
$link = mysql_connect("mysql_host", "mysql_user",
mysql_password")
or die("Could not connect : " . mysql_error());
echo "Connected successfully";
mysql_select_db("my_database") or die("Could not select
database");

/* Performing SQL query */
$query = "SELECT * FROM my_table";
$result = mysql_query($query) Loop through each row
or die("Query failed : " . mysql_error()); of the result set

/* Printing results in HTML */
echo "<table>n";
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
echo "t<tr>n";
foreach ($line as $col_value) { Loop through each
echo "tt<td>$col_value</td>n"; element in a row
}
echo "t</tr>n";
}

/* Free resultset */
mysql_free_result($result);

/* Closing connection */
mysql_close($link);
?>

 Using mysql_real_escape_string()
 Using of string replace method for SQL
keywords like SELECT, INSERT, DELETE and
UPDATE

Database Basics and MySQL

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