Relational database - June 17, 2010 at 11:20 AM by Rajmeet Ghai
What is Rational database? Flat database vs. Rational database
Features of Rational database
Dr. Codd defined thirteen standards which must be met before a database can be
considered to be a relational database. What was that?
Explain how data is arranged in a rational database with an example.
What is Rational database? Flat database vs. Rational database
A relational database looks for relativity in the database. This means that it
has a set of tables with predefined meanings and it matches data using some
common attributes found in the data set.
A flat file database restricts user to define the data types and columns one
table at a time. Any plain text file could be an example of this. On the other
hand relational database allows data types and columns to be defined for
multiple tables and thereby permitting a relationship between them.
Features of Rational database
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A relational database is created and defined using SQL queries.
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It allows the columns to have constraints like primary key, NOT NULL and
foreign keys for consistency and integrity of data.
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It allows additional features like stored procedures, indices for faster data
retrieval.
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It allows you to perform server complex calculations using an array of
operators.
Dr. Codd defined thirteen standards which must be met before a database can be
considered to be a relational database. What was that?
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Relational capabilities must be used in order to manage such databases.
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Information in a database should be interpreted only through values of tables,
columns etc
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The information can be accessed using a combination of the table name, primary
key value, and column name.
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support for the treatment of null values, distinct from default values and
independence of domain should be provided.
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In order to describe a database, logical level like tables should be made use
of.
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At least one supported language must have a well-defined syntax and be
comprehensive. It must support data definition, manipulation, integrity rules,
authorization, and transactions.
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The system should be capable of updating views
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It should allow set-level inserts, updates, and delete apart from set-level
retrievals
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On altering physical access methods or storage structures, Application
programs and ad hoc programs should be unaffected to maintain Physical data
independence
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In order to maintain logical data independence, application programs and ad
hoc programs shouldn’t be logically affected.
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The database should be capable of defining integrity rules
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On distributing and redistributing data, Application programs and ad hoc
requests are logically unaffected.
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Integrity rules cannot be bypassed using lower-level languages
Explain how data is arranged in a rational database with an example.
Data in a relational database is arranged with the help of tables. A table is a
logical entity that has columns and rows. Each table has values that represent
data.
Example:
Table employee has the fields id, name, salary. Here, the columns are id, name
and salary while their values will be data.
-Introducing data manipulation language(DML)
RDBMS is a database management system based on relational model defined
by...RDBMS stands for Relational Database Management System..........
Tables, indexes, views, synonyms, sequences, ... In the terms of a relational
database, one can call a table as an entity and the.......
Explain Row level and statement level trigger, What is a join, explain the types
of joins?, Differences between CHAR and NCHAR in Oracle, Differences between
DATE and TIMESTAMP in Oracle, Explain the attributes of implicit
cursor.............
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