History of Database Applications
Databases and database management systems have become a very
essential part of today’s information systems.
In the 1960’s, two main data models were developed .
Network model - CODASYL (Conference on Data System Language)
Hierarchical model IMS (Information Management System).
The relational database model was invented in 1970’s by E.F. Codd. the standard principal of database systems.
Mainframe computers cost hundreds of dollars per minute to operate.
The early databases used rigid hierarchical structures and the physical linking or nesting of the data on magnetic tapes.
In his 1970 paper “A Relational Model of Data for Large Shared Data Banks,” Codd envisioned a software architecture that would enable users to access information without expertise in the database’s physical blueprint.
Database that could organize information into related tables based on common characteristics.
Retrieve an entirely new table from data in one or more tables with a single query.
Understanding the relationships among all of their data in order to gain insights for making decisions.
“Ted’s basic idea was that relationships between data items should be based on the item’s values, and not on separately specified linking or nesting,” said Don Chamberlin, best known as co-inventor with Raymond Boyce of Structured Query Language (SQL).
“This greatly simplified the specification of queries and allowed unprecedented flexibility to exploit existing data sets in new ways. He believed that computer users should be able to work at a more natural language level and not be concerned about the details of where or how the data was stored.”
Donald Chamberlin and Raymond Boyce, inventor of SQL (Structured Query Language), the world's most widely used database language. Developed in the mid-1970s, SQL was the first commercially successful language for relational databases. Chamberlin was also one of the managers of IBM's "System R" project, which produced the first SQL implementation and developed much of IBM's relational database technology.
IBM developed the prototype system called System R.
During 1980’s, relational system began to commercialized and
the concept of the object-oriented database was developed.
In 1990’s, developments were more focused on the client tools such
as Oracle Developer and VB.
Interactive applications appeared and there is a growing trend to
provide more sophisticated programming logic within the database
structure.
The Sixties
Cobol and later Fortran, the first
non-proprietary programming language has been developed.
Main data models were developed,
Network model by C.W.Bachman (Bachman 1965)
Hierarchical model IMS (Information Management System).
IBM created the very first commercial system IMS for American Airlines to help them store reservation data.
Both kinds of DBMSs (hierarchical and network) were accessible
using Cobol, which makes it controllable to maintain and manage
the database.
The Seventies
"A Relational Model of Data for Large Shared Data Banks". In the paper,
Codd stated that all the data in a database could be represented as a tabular structure (tables with columns and rows).
In the past, database applications were considered to search for data only by content instead of following links.
in 1976, Peter Chen entity-relation model. And it serves as the foundation of many systems analysis and design methodologies.
The Eighties
Deal with large scales of data and complicated objects.
The database had to be able to store classes and objects and the objects associations and methods, and the object-oriented DBMS (OODBMS) appeared.
Several companies had invented OODBMSs (e.g. ObjectDesign, Versant).
Also, SQL has become the standard query language since then.
RDBMS was beginning to be widely used in the market.
The Nineties
Client tools for application development, such as PowerBuilder
(Sybase), Oracle Developer, and VB (Microsoft).
The client-server model for computing served as the norm.
CGI (Computer Generated Imagery), Apache, and MySQL. Online
Transaction Processing (OLTP) and Online Analytical Processing
(OLAP) became much more popular because of the wide application of POS.
Early 21st Century
The development of PDAs (Personal Data Assistants), consolidation of vendors, transections and interactive database applications have been created.
Storing and retrieving data, the database application began to adopt
more sophisticated programming language and more advanced features like triggers, cascading update, and delete.
This makes database run more consistently within tables.
Database Types:
A database (DB) is basically grouped amount of data organized in
a way that allows a computer program termed the Database.
A database management system (DBMS) is a collection of software
programs that gives a user the interaction ability to store, modify
and extract data from a certain database.
Relational Model
A Relational Database Management System (RDBMS) is a system
where a relation is defined as a set of tuples represented by a table.
Each column in the table contains data of the same type.
Business rules are implemented in this kind of database by employing
constraints to provide restrictions on the kinds of data to be stored.
Relations’ tuples are identified by unique fields called keys. The
relational database can be accessed rapidly by an index as it allows
direct look-up rather than checking all tuples.
The structured query language (SQL) is the computer language that
deals with relational databases.
It is used to perform common operations like data storage and retrieval on the database.
The relational database deals with undefined or missing
information by a three-valued logic where test results would be
True, False or Null.
The data in the relational model are represented
as a mathematical n-ary relation.
Each row in a table represents one n-tuple of a relation and cardinality is defined as the number of tuples in a relation. A tuple of a relation is considered a set, thus there is no defined ordering in a relation.
A transaction is a transformation of state which has the properties of atomicity, consistency, isolation and durability, ACID.
Structured Query Language (SQL)
The most popular and widely used database language SQL which
was initially called SEQUEL.
Designed by IBM to retrieve and manipulate data in their database.
Included common operations like insert, delete, update, query, schema creation and modification.
The most common operation in SQL is the query command, also
known as SFW. It is performed by the SELECT statement to
retrieve data FROM one or more tables WHERE target tuples
satisfy certain conditions.
The Data Manipulation Language (DML) is a subset of SQL used
to add, update and delete data. The Data Definition Language
(DDL) manages table and index structure.
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