chapter 12 Databases and database management systems

NoSQL databases

(Not only SQL) refers to a wide variety of different database technologies that were developed in order to overcome some of the limitations of relational database.

attribute

A characteristic of an entity

record

A collection of fields that appear as a row in a database or table.

Database

A collection of related data that is stored in a manner enabling information to be retrieved as needed; in a relational database, a collection of related tables.

centralized database system

A database system in which all of the data used by the system is located on a single computer.

database system

A database system in which the data used by the system is located on multiple computers that are connected via a network.

client server database systems

A database system where the database is located on a server and accessed by client devices.

in memory database

A database that stores all data in memory instead of on a storage medium; also called a main memory database (MMDB)

cloud databases

A database typically hosted on a cloud database providers servers, that is accessible to users via the web. (Amazon).

report

A formatted way of looking at information retrieved from a database table or the results of a query.

Form

A formatted way of viewing and editing a table in a database.

indexed organization

A method for organizing data on a storage medium or in a database that uses an index to specify the exact storage location.

File Management

A program that allows the creation of individual databases (flat files) can work with only one table at a time, each table has to contain all the data that may need to be accessed or retrieved at one time, much higher level of redundancy.

field

A single category of data to be stored in a database, such as a person's last name or phone number; also called a column.

index

A small table containing a primary key and the location of the record belonging to that key; used to locate records in a database.

Primary Key

A specific field in a database table that uniquely identifies the records in that table (used to identify each record in the table).

multidimensional databases (MDDB)

A type of database optimized for data warehouse applications. stores a collection of summarized data for quick and easy analysis, (enterprise wide activities) can be viewed from multiple perspectives called dimensions.

Hybrid XML/relational database

A type of database system that can store and retrieve both XML data and relational data.

Database Management System (DBMS)

A type of software program used to create, maintain, and access databases. (controls the organization of the data and protects the integrity and security of the data so it is entered accurately into the database).

SQL Injection

An attack that targets SQL servers by injecting commands to be manipulated by the database.

Database developers

Create the actual database based on the design generated by the data base designer and get it ready for data entry. (includes setting up the database structure and creating the user interface).

Relating Data

Data in various tables can be pulled together by their common field (product number).

Input Mask

L000 to specify the format, one letter and three numbers

Data Hierarchy

Lowest level: characters are entered into database fields (columns), next level: groups of related fields , next: tables made up of related records, at the top is the database which consists of a group of related tables.

PHP Script

PHP Hypertext preprocessor is a scripting language that is increasingly being used to create dynamic web pages, code is similar to Perl and C++ that's inserted into the HTML code of a web page using special PHP tags, they are highly compatible with many types of databases.

data security

Protecting the data located in a database against destruction and misuse.

data privacy

Protecting the privacy of the data located in a database.

Database Designer

The individual responsible for designing a database. (work with systems analyst and others involved in the system development life cycle) some times referred to as data architects, database engineers, and database analysts.

Users

The individual who enter data, update data, and retrieve information from the database when neccessary; that is the individuals who use the database.

Relationable Database

The type of database most widely used at the present time.

Query

When the user supplies a product number and order size, all other relevant information needed to complete an Order Request screen is gathered and displayed automatically.

direct organization

a method of arranging data on a storage medium that uses hashing to specify the exact storage location.

data integrity

accuracy of data

data Manipulation

adding, modifying, or deleting records or retrieving information from the database.

middlware

additional tier that contains software needed to connect the client and server components of the database system.

Object Query Language (OQL)

an object oriented version of sql

In-Memory Analytics

analyzing data that resides in a computers RAM instead of on storage media is called in memory analytics.

single user database systems

are located on a single computer and are designed to be accessed by one user, accessed via a network.

one-to-many relationships

are the most common type of relationship. A one-to-many relationship means that a single record from one table could be associated with more than one record from the other table, but a record from the second table can only be associated with one record from the first table. An example of the one-to-many relationship would be the relationship between orders and customers. A customer can place more than one order, but an order will only belong to one customers.

database administrators (DBAs)

are the people responsible for managing the databases within an organization. ( perform regular maintenance, assign and monitor user access to the database, monitor the performance of the data base system, perform backups, and carry out other necessary maintenance and security duties.

Data Organization

arranging data for efficienct retrieval.

Record Validation Rules

can also be assigned to a table, when appropriate; these rules are checked after all fields in a record are completed but before the record is saved.

CGI Scripts

common gateway interface is a set of instructions written in a programming language (C, Perl, Java, or Visual basic) designed to accept data from and return data to a web page visitor. Can slow down server response time because they process each request individually.

data dictionary

contains all data definitions for a database, including table structures.

database programmer

custom programs used to access the database or to tie the database to other applications, such as to a web site for an e-commerce application. (can both the database developer and database programmer; may function as the database developer.

Metadata

data about data, such as the data contained in a data dictionary.

relationship

describes an association between two or more entities.

hashing algorithm Remainder

dividing the primary key field by a particular prime number, the prime number is determined by the number of records to be stored or the number of storage areas to be used. the REMAINDER of this division procedure becomes the address at which the record is physically stored.

Active Server Pages (ASP)

dynamic web pages that have the extension .asp, the code to tie the database to the web site is typically written in javascript or vbscript.

query

extracts specific information from a database by specifying particular conditions called criteria about the data you would like to retrieve.

2 Tier Model

has just two parts a client and a server. (commonly used in e commerce database applications).

per transaction

if invalid data is supplied and not corrected at some point during the steps necessary to enter a complete transaction into the system , then the entire transaction will fail, ensuring a valid transaction will be complete.

data definition

involves describing the properties of the data that go into each database table , specifically the fields that make up the database (name: unique within the table, Data type: short text, long text , number , currency , yes/no, hyperlink, or date/time, Description: optional description, and properties: field size and format).

Object oriented database management system (OODBMS)

is often able to store and retrieve complex, unstructured data better than a relational database management system. Store data in objects

relational database management systems

is the most widely used database model today. In which data is stored in tables related by common fields, tables are independent but data can be retrieved from related tables via primary key fields when needed.

multi-user database system

may try to access and modify the same data at the same time, some type of database locking must be used to prevent users from making conflicting changes to the same data at the same time.

Database activity monitoring program (DAM)

monitors a database continually to detect and report possible intrusions, vulnerabilities, and other threats in real time; it also updates its knowledge base of known database security threats automatically to protect against new threats automatically to protect against new threats as they become known.

Online analytical Processing OLAP

most common type of software used in conjunction with a multi-dimensional database.

n tier database systems

one middle component or tier between the client and the server

Database locking

row locking: an entire table row is locked when any part of that record s being modified. Column level locking: in which the table column involved in the changes is locked until the changes to that field have been completed.

entity

something (person, object, or an event) that is important to a business or an organization; typically becomes a database table in a data base system for that business or organization.

Database encryption software

stronger database encryption tools are also being integrated into DBMSs.

Third Normal Form (3NF)

table in 2nf with no transitive dependencies that is two fields that are not primary keys and are dependent on one another, such as the supplier name,number fields in a product table, these dependent fields are placed in a separate table and related to the original table via a primary key field.

front end

the client

Dynamic web pages

the content changed based on the users input or stated preferences.

back end

the database server

sequenced organization

the order of the records is physically based on the content of the key field. ( use with batch processing using a sequential access medium, not frequently used today.

The evolution of databases

the organization of data has evolved from a collection of independent flat files with tree or branching structures and high levels of data redundancy, to a collection of tables and objects that support multimedia objects with a minimum of data redundancy, and databases that can be viewed from a variety of perspectives or dimensions.

Data Validation

the process of ensuring that data entered into a database is valid (matches the data definition).

Normalization

the process of evaluating and correcting the structure of a database table to minimize data redundancy.

structured query language (SQL)

the standard query language for relational database. (query design screen or query wizard) to create a query object.

First Normal Form (1NF)

the table has unique fields, no repeating groups, all fields are dependent on the primary key, any repeating groups have been placed in a second table and related to the original table via a primary key field.

Second Normal Form (2NF)

the table is in 1nf with no partial dependencies that is fields in a table that dependent on part of the primary key and all fields are dependent on a single primary key or on all of the fields in a composite primary key. (any partial dependencies have been removed and these dependent fields are placed in a separate table and related to the original table via a primary key field.

committed

until all steps in the transaction are deemed valid and the appropriate ate changes are to all the affected tables.

collision

usually result in two or more records being assigned the same storage address.

many-to-many relationships

when one entity can be related to more than one other entity, and those entities can be related to multiple entities of the same type as the original entity.

one-to-one entity relationships

when one entity is related to only one other entity of a particular type.

Hashing algorithm

with direct organization, the computer uses each records primary key field and a mathematical formula to determine a unique address that identifies where the record is physically stored in the database file.