int survey #8...

**BACKGROUND OF POSTGRESQL

PostgreSQL is an object-relational database management system (ORDBMS). It is released under a BSD-style license and is thus free software. PostgreSQL is not controlled by any single company, but relies on a global community of developers and companies to develop it.The mixed-capitalization of the PostgreSQL name can confuse some people on first viewing. The several pronunciations of 'SQL' can lead to this confusion. However, the PostgreSQL Core Team announced in 2007 that the product would continue to be named PostgreSQL. The name refers to the project's origins as a "post-Ingres" database, the original authors having also developed the Ingres database.

PostgreSQL includes built-in support for B+-tree, hash, GiST and GiN indexes. In addition, user-defined index methods can be created, although this is quite an involved process. Indexes in PostgreSQL also support the following features:

*PostgreSQL is capable of scanning indexes backwards when needed; a separate index is never needed to support ORDER BY field DESC.
*Expression indexes can be created with an index of the result of an expression or function, instead of simply the value of a column.
*Partial indexes, which only index part of a table, can be created by adding a WHERE clause to the end of the CREATE INDEX statement. This allows a smaller index to be created.
*The planner is capable of using multiple indexes together to satisfy complex queries, using temporary in-memory bitmap index operations.

**DIFFERENCE BETWEEN MEMORY VARIABLE AND DATABASE FIELD

Memory variable is an attribute of a physical or an abstract system which may change its value while it is under observation while database fields are the basic units of data storage, and each field typically contains information pertaining to one aspect or attribute of the entity described by the database.

**DIFFERENCE BETWEEN DATABASE RECORD AND DATABASE FIELD

The difference between database field and database record is that, database fields are the basic units of data storage, and each field typically contains information pertaining to one aspect or attribute of the entity described by the database while database records are organized into tables that include information about relationships between its various fields.

ERRATUM

Sir, hi! ;)

i made this post just to make corrections.. i just noticed that my BLOG NUMBERING is not right. but then, i opted not to change it since the dates will be changed to0. sorry sir. ;)

take care and Godblesssss... ;)

int survey#8..

**WHAT IS NORMALIZATION?

**ANSWER:

Database normalization, sometimes referred to as canonical synthesis, is a technique for designing relational database tables to minimize duplication of information and, in so doing, to safeguard the database against certain types of logical or structural problems, namely data anomalies. For example, when multiple instances of a given piece of information occur in a table, the possibility exists that these instances will not be kept consistent when the data within the table is updated, leading to a loss of data integrity. A table that is sufficiently normalized is less vulnerable to problems of this kind, because its structure reflects the basic assumptions for when multiple instances of the same information should be represented by a single instance only.

Higher degrees of normalization typically involve more tables and create the need for a larger number of joins, which can reduce performance. Accordingly, more highly normalized tables are typically used in database applications involving many isolated transactions while less normalized tables tend to be used in database applications that need to map complex relationships between data entities and data attributes (e.g. a reporting application, or a full-text search application).

Database theory describes a table's degree of normalization in terms of normal forms of successively higher degrees of strictness. A table in third normal form (3NF), for example, is consequently in second normal form (2NF) as well; but the reverse is not necessarily the case.

Although the normal forms are often defined informally in terms of the characteristics of tables, rigorous definitions of the normal forms are concerned with the characteristics of mathematical constructs known as relations. Whenever information is represented relationally, it is meaningful to consider the extent to which the representation is normalized.