In general, an attribute is a characteristic.
It is the name of the column.
An attribute gives the characteristics of the entity.
In a database management system (DBMS), an attribute refers to a database component, such a table.
It also may refer to a database field.
Attributes describe the instances in the row of a database.
For example,
A customer of bank may be described by : name, address, customer ID number.
It is also called as data element, data field, a field, a data item, or an elementary item.
Type of Attributes in DBMS –
  1. Single Values Attributes: An attribute, that has a single value for a particular entity is known as single valued attributes. For example, age of a employee entity.
  2. Simple/Atomic Attributes: The attributes which cannot be divided into smaller subparts are called simple or atomic attributes. For example, age of employee entity
  3. Multi Valued Attributes: An attributes that may have multiple values for the same entity is known as multi valued attributes. For example colors of a car entity.
  4. Compound/Composite Attribute: Attribute can be subdivided into two or more other Attribute. For Example, Name can be divided into First name, Middle name and Last name.
  5. Derived Attribute: Attributes derived from other stored attribute. For example age from Date of Birth and Today’s date.
  6. Key Attributes : Represents primary key. (main characteristics of an entity). It is an attribute, that has distinct value for each entity/element in an entity set. For example, Roll number in a Student Entity Type.
  7. Required Attributes: A required attribute is an attribute that must have a data value.These attributes are required because they describe what is important in the entity. For example, In a STUDENT entity, firstname and lastname is a required attribute.
  8. Complex Attributes: If an attribute fr an entity, is built using composite and multivalued attributes, then these attributes are called complex attributes. For example, a person can have more than one residence and each residence can have multiple phones, an addressphone for a person entity can be specified as – {Addressphone (phone {(Area Code, Phone Number)}, Address(Sector Address (Sector Number,House Number), City, State, Pin))}Here {} are used to enclose multivalued attributes and () are used to enclose composite attributes with comma separating individual attributes.
  9. Non Key Attributes: These are attributes other than candidate key attributes in a table. For example Firstname is a non key attribute as it does not represent the main characteristics of the entity.
  10. Optional/Null Value Attributes: An optional attribute may not have a value in it and can be left blank. For example, In a STUDENT entity, Middlename or email address is an optional attribute. as some students may not have middlename or email address.
  11. Stored Attribute: An attribute, which cannot be derived from other attribute, is known as stored attribute. For example, BirthDate of employee.

More topics from DBMS to read: covered following topics in these notes.
Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.