by Dinesh Thakur Category: RDBMS

A relation R is in Fourth Normal Form (4NF) if and only if the following conditions are satisfied simultaneously:

R is already in 3NF or BCNF.

If it contains no multi-valued dependencies.

 
by Dinesh Thakur Category: RDBMS

A relation R is in Fifth Normal Form (5NF) if and only if the following conditions are satisfied simultaneously:
1. R is already in 4NF.
2. It cannot be further non-loss decomposed.
5NF is of little practical use to the database designer, but it is of interest from a theoretical point of view and a discussion of it is included here to complete the picture of the further normal forms.



 
by Dinesh Thakur Category: RDBMS

Denormalization is the process of attempting to optimize the performance of a database by adding redundant data or by grouping data. In some cases, denormalization helps cover up the inefficiencies inherent in relational database software. A relational normalized database imposes a heavy access load over physical storage of data even if it is well tuned for high performance.



 
by Dinesh Thakur Category: RDBMS

To eliminate these anomalies in 3NF relations, it is necessary to carry out the normalization process to the next higher step, the Boyce-Codd Normal Form.
BCNF is simply a stronger definition of 3NF. Since BCNF is higher form of 3NF, so a relation in BCNF must be in 3NF. BCNF makes no explicit reference to first and second normal form as such, nor the concept of full and transitive dependence.

 
by Dinesh Thakur Category: RDBMS

A relation R is in Third Normal Form (3NF) if and only if the following conditions are satisfied simultaneously:
1. R is already in 2NF
2. No nonprime attribute is transitively dependent on the key.
Another way of expressing the conditions for Third Normal Form is as follows:
1. R is already in 2NF
2. No nonprime attribute functionally determines any other nonprime attribute.
These two sets of conditions are equivalent.

As these two definitions of 3NF imply, the objective of transforming relations into 3NF is to remove all transitive dependencies. So, first we are going to explain the concept of transitive dependency.

 
by Dinesh Thakur Category: RDBMS

A relation is said to be in First Normal Form (lNF) if and only if every entry of the relation (the intersection of a tuple and a column) has at most a single value. In other words "a relation is in First Normal Form if and only if all underlying domains contain atomic values or single value only."

 
by Dinesh Thakur Category: RDBMS

We have already seen relational algebra is a procedural language, in which user has to write the steps or procedure to obtain the required results but in general a user should not have to be concerned with the details of how to obtain information. In relational calculus user is not concerned with the procedure to obtain the results, he/she just tell his/her requirements and the output is available without knowing the method about its retrieval.



 
by Dinesh Thakur Category: RDBMS

Relational operators are classified into two types:
• Traditional Set Operators
• Special Operators

 
by Dinesh Thakur Category: RDBMS

Relational Algebra is a procedural language that can be used to tell the DBMS how to build a new relation from one or more relations in the database and the Relational Calculus is a non-procedural language that can be used to formulate the definition of a relation in terms of one or more database relations.



 
by Dinesh Thakur Category: RDBMS

What is Key?

A database consists of tables, which consist of records, which further consist of fields.

This below figure provides an example of a typical table consisting of STUDENT details:



 
by Dinesh Thakur Category: RDBMS

Dr. E.F. Codd, the founder of the relational database systems, framed twelve rules to assist a database product to qualify as relational. An RDBMS product has to satisfy at least six of the 12 rules of Codd to be accepted as a full-fledged RDBMS. There is no RDBMS package commercially available that satisfies all the 12 rules. These rules are:



 
by Dinesh Thakur Category: RDBMS

More precisely, the relational model is concerned with three components: Data Structure,Data Integrity,Data Manipulation

 
by Dinesh Thakur Category: Advanced Database Tech.

A simple, flat-file database has only a single table, which means it has one set of records with fields. Each record within the table contains the same fields with the same type of information in each field, although of course the specific information you enter into each separate field is different. For instance, you might have a "Last Name" field on every record, but the actual last name on each record is different.



 
by Dinesh Thakur Category: Advanced Database Tech.

The storing information in a data warehouse does not provide the benefits an organization is seeking. To realize the value of a data warehouse, it is necessary to extract the knowledge hidden within the warehouse. However, as the amount and complexity of the data in a data warehouse grows, it becomes increasingly difficult, if not impossible, for business analysts to identify trends and relationships in the data using simple query and reporting tools.



 
by Dinesh Thakur Category: Advanced Database Tech.

Online Analytical Processing is used to answer the complex queries posted on data warehouse. In order to solve the queries of nature 'who?' and 'what?' we can use the simple tools but to answer the advanced queries like 'what if?' and 'why?', we require special tool that can support online analytical processing (OLAP).

 
by Dinesh Thakur Category: Advanced Database Tech.

There are the three fundamentals components that are supported by data warehouse as shown in figure. These are:

 

• Load Manager

• Warehouse Manager

• Data Access Manger

 
by Dinesh Thakur Category: Advanced Database Tech.

A Database Systems have been used traditionally for online transaction processing (OLTP). OLTP systems are designed to maximize the transaction processing capacity It is commonly used in clerical data processing tasks, structured repetitive tasks, read update a few records. In OLTP isolation, recovery and integrity are critical. It is based on operational systems.

 
by Dinesh Thakur Category: Advanced Database Tech.

Today, multinational companies and large organizations have operations in many places within their origin country and other parts of the world. Each place of operations may generate large volume of data. For example, insurance companies may have data from thousands of local and external branches large retail chains have data from hundreds or thousands of stores and so on. Corporate decision maker require access of information from all such sources.



 
by Dinesh Thakur Category: Advanced Database Tech.

The acronym DBTG refers to the Data Base Task Group of the Conference on Data Systems Languages (CODASYL), the group responsible for standardization of the programming language COBOL. The DBTG final report appeared in Apri1971, it introduced a new distinct and self-contained language. The DBTG is intended to meet the requirements of many distinct programming languages, not just COBOL, the user in a DBTG system is considered to be an ordinary application programmer and the language therefore is not biased toward any single specific programming language.



 
by Dinesh Thakur Category: Advanced Database Tech.

Relational DBMSs are currently the dominant database technology. The OODBMS has also become the favored system for financial and telecommunications applications. Although the OODBMS market is still same. The OODBMS continues to find new application areas, such as the World Wide Web. Some industry analysts expect the market for the OODBMSs to grow at over 50% per year, a rate faster than the total database market.



 

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About Dinesh Thakur

Dinesh ThakurDinesh Thakur holds an B.SC (Computer Science), MCSE, MCDBA, CCNA, CCNP, A+, SCJP certifications. Dinesh authors the hugely popular blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps. For any type of query or something that you think is missing, please feel free to Contact us.