Classless addressing is a concept of addressing the IPv4 addresses. It was adopted after the failure of classful addressing. The classful addressing leads to wastage of addresses as it assigns a fixed-size block of addresses to the customer. But, the classless addressing assigns a block of addresses to the customer according to its requirement which prevents the wastage of … [Read more...] about Classless Addressing in IPv4
Classful Addressing in IPv4
Classful addressing is a concept that divides the available address space of IPv4 into five classes namely A, B, C, D & E. Nowadays, this concept has become obsolete and has been replaced with classless addressing. IP addresses, before 1993 use the classful addressing where classes have a fixed number of blocks and each block has a fixed number of hosts. In this section, we … [Read more...] about Classful Addressing in IPv4
Connection Oriented and Connectionless Services
Connection oriented and Connectionless services are the two data transmission services provided by the network layer protocols and transport layer protocols. The Connection oriented services establish a connection prior to sending the packets belonging to the same message from source to the destination. On the other hand, the connectionless service considers each packet … [Read more...] about Connection Oriented and Connectionless Services
Difference Between Entity and Attribute in Database
Entity and attribute are the most common terms of DBMS. The fundamental difference between the entity and attribute is that an entity is an object that exists in a real-world and can be easily distinguished among all other objects of real-world whereas, the attributes define the characteristics or the properties of an entity on the basis of which it is easily distinguishable … [Read more...] about Difference Between Entity and Attribute in Database
Aggregate Functions in SQL
Aggregate functions in SQL evaluates the set of tuple values and returns a relation with a single attribute carrying single tuple value as a result. SQL has five aggregate functions count, average, maximum, minimum, sum. Among these aggregate functions, only 'sum' and 'average' function operate only on numeric values only while count, maximum, minimum can also operate on … [Read more...] about Aggregate Functions in SQL
Set Operations in SQL
Set operations integrate the outcome of two entirely independent SQL queries. There are three set operations in SQL Union, Intersect, Except. These set operations are based on the principles of mathematical set theory. The set operations are applicable to the type compatible relations only, that means relations involved in operation must have an 'equal number of attributes' and … [Read more...] about Set Operations in SQL
Integrity Constraints in DBMS
Integrity constraints ensure that when the authorized users modify the database they do not disturb the data consistency. Integrity constraints are introduced while designing the database schema. The constraints are specified within the SQL DDL command like 'create table' and 'alter table' command. Let’s see, the general form of 'create table' and 'alter table' command … [Read more...] about Integrity Constraints in DBMS
Null Value in SQL
Null Value in SQL is the special value, allocated to an attribute in a relation which indicates that the information regarding the corresponding attribute is either unknown or it doesn’t even exist. In this section, we will discuss the null values in detail. What is the Null Value in SQL? The null value assigned to an attribute in a relation specifies that the value for the … [Read more...] about Null Value in SQL
SQL Data Definition Language
SQL Data Definition Language defines the set of relations in a database. SQLs DDL specifies the schema of each relation in the database and also the relevance between the relations in a database. So in this section, we will discuss SQL data definition language in detail. Content: SQL Data Definition Language Data Definition Language in SQL SQL Data Types SQL Schema … [Read more...] about SQL Data Definition Language
Relational Data Model
The relational data model provides conceptual tools to design the database schema of the relational database. The relational model describes the data, relationship between that data, data sematic and constraints on the data in the relational database. The relational model expresses the data and relationship among the data in the form of tables. There is a lot more to discuss … [Read more...] about Relational Data Model