What is database and Database Management System?
Database: It is a Organized collection of data or information.
- Stores lots of data.
- Should handle many overlapping requests.
- Usually has a schema(a predefined structure).
- Usually preserves structure correctness.
Then we may get some questions.
How do i create a database?
where i can store the information or data?
how do i use database? and how i maintain the database?
All these questions answered by a software program called "Database Management System (DBMS)" means it manages the database.
Initial research
In 1960 charles Bachman started working on Integrated Data Storage(IDS), one of the first database management system. According to Bachman, data is stored in the form of linked records. In 1960-1970 two database management systems came out IDS by CODASYL and IMS by IBM.
Approach: Manually navigate a linked data set which forms a huge network of data. When database first opened by DBMS, the DBMS gets pointer to first record and other link pointers.then DBMS will navigate to data sets manually.
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| Charles Bachman |
In 1970's Edgar F. codd invented Relational Model for Database management while working for IBM. This is the probably one which changes the Database Management System. According to Codd data stored in the form of tables and these tables maintain relations using keys.
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| Edgar Frank "Ted" Codd |
- Foundation Rule
A relational database management system must manage its stored data using only its relational capabilities. - Information Rule
All information in the database should be represented in one and only one way - as values in a table. - Guaranteed Access Rule
Each and every datum (atomic value) is guaranteed to be logically accessible by resorting to a combination of table name, primary key value and column name. - Systematic Treatment of Null Values
Null values (distinct from empty character string or a string of blank characters and distinct from zero or any other number) are supported in the fully relational DBMS for representing missing information in a systematic way, independent of data type. - Dynamic On-line Catalog Based on the Relational Model
The database description is represented at the logical level in the same way as ordinary data, so authorized users can apply the same relational language to its interrogation as they apply to regular data. - Comprehensive Data Sublanguage Rule
A relational system may support several languages and various modes of terminal use. However, there must be at least one language whose statements are expressible, per some well-defined syntax, as character strings and whose ability to support all of the following is comprehensible: - data definition
- view definition
- data manipulation (interactive and by program)
- integrity constraints
- authorization
- transaction boundaries (begin, commit, and rollback).
- View Updating Rule
All views that are theoretically updateable are also updateable by the system. - High-level Insert, Update, and Delete
The capability of handling a base relation or a derived relation as a single operand applies nor only to the retrieval of data but also to the insertion, update, and deletion of data. - Physical Data Independence
Application programs and terminal activities remain logically unimpaired whenever any changes are made in either storage representation or access methods. - Logical Data Independence
Application programs and terminal activities remain logically unimpaired when information preserving changes of any kind that theoretically permit unimpairment are made to the base tables. - Integrity Independence
Integrity constraints specific to a particular relational database must be definable in the relational data sublanguage and storable in the catalog, not in the application programs. - Distribution Independence
The data manipulation sublanguage of a relational DBMS must enable application programs and terminal activities to remain logically unimpaired whether and whenever data are physically centralized or distributed. - Nonsubversion Rule
If a relational system has or supports a low-level (single-record-at-a-time) language, that low-level language cannot be used to subvert or bypass the integrity rules or constraints expressed in the higher-level (multiple-records-at-a-time) relational language.
By using Codd's invention "Ingres Database Management system" was developed at the University of california, berkeley in 1973. Ingres has became base for number of commercial database applications like Sybase, Microsoft SQL server, Nonstop SQL,Informix. And based on Codd's paper another database has developed by IBM i.e SystemR and based on SystemR Oracle database has established. In 2012 Oracle 11g has released.
| RDBMS Vendors | RDBMS |
| Computer Associates | INGRES |
| IBM | DB2 |
| INFORMIX Software | INFORMIX |
| Oracle Corporation | Oracle |
| Microsoft Corporation | MS Access |
| Microsoft Corporation | SQL Server |
| MySQL AB | MySQL |
| PostgreSQL Dvlp Grp | PostgreSQL |
| Sybase | Sybase 11 |
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