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It is the process of discovering interesting knowledge, such as patterns, associations, changes, anomalies from large amounts of data stored in databases.

A table is a collection of data elements organised in terms of rows and columns.

Normalization is the process of reorganizing data in a database by eliminating duplication and ensuring data dependencies.

It is a field in table that uniquely identifies a record (e.g. Register number of a student).

The symbol notion for project is \(\pi\) (pi)

A database is a collection of logically related data organized in a way that data can be easily accessed, managed and updated. In colleges, student admission details, fee payment details (annual, monthly, late payment), statement of marks etc., can be maintained and various reports can be generated time to time.

A data warehouse (DW) is a database used for reporting. The data is offloaded from the operational systems for reporting.

Data means collected facts, figures and statistics. The data may be in the form of letter, symbols, numbers, images, videos and sound. It can be collected from various sources inside and outside of an organization or any part of universe.

JOIN is used to combine related tuples from two relations i.e., combines attributes of two relations into one. In its simplest form, the JOIN operator is just the cross product of the two relations.

The various data types supported by DBMS are integer, single’precision, double precision, character, string, memo, index, currency; date and text fields.

The Cartesian Product is also an operator that works on two sets. It is sometimes called the CROSS PRODUCT or CROSS JOIN. It combines the tuples of one relation with all the tuples of the other relation.

Generalization is the process of taking the union of two or more lower level entity sets to produce a higher-level entity sets. Generalization is a bottom-up approach. 

For example,entities savings account and a current account can be generalized to accounts.

Selection:
Selects tuples from a relation whose attributes meet the selection criteria, which is normally expressed as a predicate. For example, find all employees born after 14^th February 2000.

Relational algebra is a formal system for manipulating relations. Operands of this algebra are relations (a set of tuples). Operations of this algebra include the usual set operations, and special operations defined Tor relations.

The applications of database are banking, water meter billing, rail and airlines, colleges, credit card transactions, telecommunication, finance/sales, manufacturing and human resources.

It is a top-down approach in which one higher-level entity can be broken down into two lower level entities. For example, entity accounts can be broken down into savings account and current account.

• In sequential access data is stored at random locations.
• In direct access data is stored at sequential locations.
• Data structure implementing Sequential access is linked list.
• Data structure implementing Direct access is an Array.

The various types of keys used in database are candidate key, primary key, secondary key, super key and foreign key.

The advantages of disadvantages of index sequential access method are:

Advantages:

• It combines both sequential and direct
• Suitable for sequential access and random access.
• Provides quick access to records.

Disadvantages:

• It uses special software and is expensive.
• Extra time is taken to maintain index.
• Extra storage for index files.
• Expensive hardware is required.

It is processed data with definite meaning. Information gives meaning.

Data is a collection of facts, figures or statistics. Data is transformed into meaningful information. It is raw material of information.

Each row of a table is called entity instance.

An entity is a person, place, thing or event for which data is collected and maintained.