In this article, we will discuss two open source database management system i.e. MySQL and PostgreSQL. Where MySQL is the product of Oracle Corporation and PostgreSQL is the product of Global Development Group. Which one is best to use? The answer to this question varies from programmer to programmer. This depends on the requirement of the application or website that a programmer is creating. Both MySQL and PostgreSQL differ in many aspects. Let us discuss the differences between MySQL and … [Read more...]

So far, we have talked about original tables stored in the physical form in databases. In which we have access to all the attributes of the tables. What if we have to restrict a user from accessing some attributes of the table and let access the other attributes. Like, a clerk in an administrative department can search the name, address, designation, age and such other factors of an employee table. But he must not be authorized to view or access the salary of any employee. In such cases, … [Read more...]

Talking about the Strong and Weak entity, we must know what does an entity means. An entity is a unique object in the real world. It is described as the set of attributes. The collection of the same type of entities together forms the entity set. Here, we will discuss two types of entities Strong entity and Weak entity. The weak entity always depends on the strong entity for its existence. Let us discuss the differences between both, the Strong entity and weak entity with the help of … [Read more...]

Keys are the essential elements of any relational database. It identifies each tuple in a relation uniquely. Keys are also used to establish the relationship among the tables in a schema. In this article, we will discuss two basic keys of any database that is super key and candidate key. Every candidate key is a super key but, every super key may or may not be a candidate key. There many other distinguishing factors between super key and candidate key, which I have briefly discussed in the … [Read more...]

Relational Algebra and Relational Calculus are the formal query languages for a relational model. Both form the base for the SQL language which is used in most of the relational DBMSs. Relational Algebra is a procedural language. On the other hands, Relational Calculus is a declarative language. Relational Algebra and Relational Calculus can be further differentiated on many aspects, which I have discussed below with the help of comparison chart. Content: Relational Algebra Vs Relational … [Read more...]

OLAP is a common term between ROLAP and MOLAP which stands for Online Analytical Processing. OLAP is a specialized tool that creates a multidimensional view of data for the user to do the analysis. ROLAP and MOLAP are two models of OLAP. Though they are different in many aspects, the most important difference between them is ROLAP provides data, directly from main data warehouse whereas, MOLAP provides data from the proprietary databases MDDBs. Let us view some more differences between … [Read more...]

Normalization is a method that removes redundancy from a relation thereby minimizing the insertion, deletion and update anomalies that degrade the performance of databases. In this article, we will differentiate among two higher normal forms i.e. 3NF and BCNF. The basic difference between 3NF and BCNF is that 3NF eliminates the transitive dependency from a relation and a table to be in BCNF, the trivial functional dependency X->Y in a relation must hold, only if X is the super key. Let … [Read more...]

Earlier we have discussed the differences between Inner Join and Outer Join, where we have overviewed the types of Outer Join. Outer Join is the one who preserves the tuples in the result which would have been lost while Join operation. In this article; we are going to discuss the differences between the types of Outer Join. There are three types of Outer Join; Left Outer Join, Right Outer Join, and Full Outer Join. The Left, Right, and Full Outer Join differs in their execution plan, and the … [Read more...]

Keys are the crucial part of DBMS they are used to identify and establish a relation between the tables in a schema. Now, today we are going to discuss two very important keys of DBMS i.e. Primary key and Foreign key, and we will also discuss the difference between primary key and foreign key. On the way let me tell you the basic difference between primary and foreign key which is primary key is one of the chosen candidate keys by database designer whereas, a foreign key is a key that refers … [Read more...]

The Fact Table and Dimension Table, are the essential factors to create a schema. A fact table's  record is a combination of attributes from different dimension tables. Fact table helps the user to analyze the business dimensions which helps him in decision taking to improve his business. On the other hands, dimension tables help fact table to collect dimensions along which the measures has to be taken. The point that distinguishes Fact table and Dimension table is that the dimension table … [Read more...]