Page 204 - Computer - 10(A&B)

A database consists of fields, records, and table.

v Fields: The information in a table is stored column-wise. These columns are also known as Attributes. Fields
are the columns in a table which describe the individual aspect of each object in that table.
v Records: The information in a table is stored row-wise. These rows are also known as Tuple. Records are the
rows in a table that describes all aspects of an individual object in that table.
v Table: Table can be defined as a group of related data organised in the form of rows and columns.

v Data or Value: A value is a set of characters, text, or numbers that you put in while adding information to
the table.
Fields

Primary key R.No First Name Last Name Age

1 Akash Gupta 15
Records
2 Arti Negi 14

Data Value

v Primary Key: A table should have at least one field that has a unique value for each record. This field is
called the Primary key of the table. For example, in a school database, the roll number of each student
uniquely Identifies each student. Two students can have the same name, but they can never have the same
roll number. So, the roll number field is the primary key.
) A primary key does not allow null values.

) A primary key must always have a unique value.
v Composite Primary Key: A primary key is an attribute/column that can uniquely identify each row of a
table. When more than one attributes are required to uniquely identify a row in a table, the resulting primary
key that is made of the combination of these attributes is known as Composite key. These attributes in this
particular combination can be used for uniquely identifying each row in the table, however, when they are
taken individually, it does not guarantee any such unique identification. Attributes/Columns that make up
the composite key can be of different data types.
v Foreign Key: A foreign key is an attribute/column or a combination of attributes/columns whose values
match a primary key of a different table. This matching allows the two tables to be linked together.

Database Management System
A computer based application used to create, store, and manipulate a database is called Database Management
System (DBMS). It helps in quick retrieval of processed information from the large complicated databases. This
is a specialised application which can perform different types of operations on the stored data like extracting
specific piece of information based on user’s criteria, generating formatted reports for the efficient data analysis,
etc.

Some of the popular Database Management Systems are—Microsoft Access, LibreOffice Base, Oracle, Microsoft
SQL Server, MySQL, and Sybase.

Need for Database

Databases are used to store information in a structured manner such that they are independent of the programs
or applications. Information in the database is stored in the form of tables made up of rows and columns, wherein
the data values stored horizontally along a single row represent the complete information about an individual
entity in that table. The information stored along the column vertically, represent single category of information

86