Data warehouse can be defined as the integrated, subject oriented and non volatile collection of data. The data collected in warehouse help analysts in organized decision making. The data stored can undergo frequent changes on daily basis. The warehouse data will provide an overview about a product which will further assist in improving the business. […]
Difference Between Class and Primitive Types
All the variables declared in Java are classified into certain type. The classification of variables will help us in treating the variables according to its type. Variables in Java are classified as characters, several types of integers, floating points and types to declare a statement true or false. All the above mentioned variable types are […]
Database Roles in SQL
Database role can be defined as the collection privileges assigned one or several users. Each database role is given a name. Most RDBMS platforms have set of predefined roles assigned to a user. Every user with CREATE ROLE privilege can create his/her own database role. Roles in database allow a user to set up hierarchical […]
Difference Between Correlated and Uncorrelated Subquery
What is Correlated Subquery? Correlated subquery can be defined as the inner query referenced by the outer query. The outer query reference the inner query for repeated execution. Correlated subqueries will contain the references to the objects present in the parent statement. The operation of correlated subquery depends upon the evaluated row in the parent […]
Difference Between Having and Where Clauses
The difference between Having and Where clause is one of the most commonly asked database interview questions. The most answer by many aspiring developers is Where clause is used to select any queries while Having clause is used in queries containing aggregate function. Both definitions are correct but when they are asked to explain the […]
What is Secondary Key?
The questions about secondary key in SQL is common in most database interviews. The Candidate keys which are not selected as primary key is classified as Secondary key. Consider that you have a table, there will be several keys in a table which can be selected as a primary key. The keys which has the […]
What is Referential Integrity?
Referential integrity in RDBMS can be defined as a consistent relationship shared between tables present in a database. In other words, the foreign key references used in a database must agree with the references of primary key. The set of referential integrity constraints can applied to foreign key to prevent a row from entering inside […]
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