In this post, we will understand the difference between star schema and snowflake schema.Star SchemaHierarchies of dimensions are stored in a dimensional table.It contains a fact table that is surrounded by dimension tables.In this schema, a single join creates the relationship between a fact table and any dimension tables.It is a simple database design.It has high levels of data redundancy.The processing of cube is quick.A single dimension table contains the aggregated data.It is a de-normalized data structure.The queries run quickly in comparison to other schema.It uses start join query optimization technique. Hence, the queries perform well.Tables can be connected with ... Read More

In computer science and information technology, the terms data and information are frequently used as if they are synonyms, but in reality, they are quite different from each other. The most fundamental difference between the two is that data is the collection of raw facts and figures, while information is the processed data that have a meaning for a user. Read this article to find out more about "data" and "information" and how these two terms are different from each other. What is Data? Data is a collection of raw facts and figures that can be processed by any computing ... Read More

In this post, we will understand the difference between MySQL and PostgreSQL.MySQLIt is a relational database management system.It is the product developed by Oracle Corporation.It is supported by Windows, Mac OS X, Linux, BSD, UNIX, z/OS, Symbian, AmigaOS.It can’t be extended.In this system, the phpMyAdmin tool gives the GUI.Mysqldump and XtraBackup provide backup in MySQL.It provides temporary table.It doesn’t provide a materialized view.It doesn’t provide Data Domain Object to the system.PostgreSQLIt is an object-relational database management system.It was developed by the Global Development Group.It is supported by Windows, Mac OS X, Linux and BSD but not by UNIX, z/OS, Symbian, ... Read More

In this post, we will understand the difference between WHERE clause and HAVING clause in SQL.WHERE ClauseIt is used to filter the records from the table based on a specific condition.It can be used without the ‘GROUP BY’ clause.It can be used with row operations.It can’t contain the aggregate functions.It can be used with the ‘SELECT’, ‘UPDATE’, and ‘DELETE’ statements.It is used before the ‘GROUP BY’ clause if required.It is used with a single row function such as ‘UPPER’, ‘LOWER’.HAVING ClauseIt is used to filter out records from the groups based on a specific condition.It can’t be used without the ... Read More

DELETE is a Data Manipulation Language (DML) command. It is used to remove tuples/records from a relation/table. On the other hand, DROP is a Data Definition Language (DDL) command and is used to remove named elements of schema like relations/table, constraints or entire schema. Read this article to learn more about DELETE and DROP commands in SQL and how they are different from each other. What is DELETE in SQL? In SQL, the DELETE command is used to remove some or all the records from a database table. With the DELETE command, the WHERE clause is used to define the ... Read More

In this post, we will understand the difference between COMMIT and ROLLBACK in SQL.COMMITIt validates the modifications that are made by the current transaction.Once the COMMIT statement has been executed, the transaction can’t be rolled back using ROLLBACK.It occurs when the transaction is successfully executed.SyntaxCOMMIT;ROLLBACKIt removes the modifications that were made by the current transaction.Once ROLLBACK is executed, the database would reach its previous state.This is the state where the first statement of the transaction would be in execution.ROLLBACK happens when the transaction is aborted in between its execution.SyntaxROLLBACK;

In this post, we will understand the difference between clustered index and non-clustered index.Clustered indexIt is quick.It requires less memory to perform operations.The index is the main data.A table can have one clustered index only.It has inherent ability to store data on the disk.It can store pointers to block not to data.The leaf nodes contain actual data.The clustered key defines the order of data within table.It is a type of index where the table records are physically reordered to match with the index.Non-clustered indexIt is slower.It requires more memory to perform operations.The index is a copy of data.A table can ... Read More

In this post, we will understand the difference between grant and revoke.GrantIt is a DCL command.It grants permissions to users on database objects.It can also be used to assign access rights to users.For every user, the permissions need to be specified.When the access is decentralized, permission granting is easier.Syntax:grant privilege_name on object_name to {user_name | public | role_name}RevokeIt is a DCL command.It removes permissions if they are granted to users on database objects.It takes away/revokes the rights of the users.If access for a user is removed, all specific permissions provided by that user to others will be removed.If decentralized access ... Read More

Descriptive data mining and predictive data mining are mining techniques that are used to find useful information and patterns in large datasets. Descriptive data mining is a data mining technique that analyzes the past data to provide latest information on past events, while predictive data mining is a data mining technique that is used to analyze past data and provides answers of future queries. Read this this article to learn more about descriptive and predictive data mining techniques and how they are different from each other. What is Descriptive Data Mining? Descriptive data mining is a data mining technique that ... Read More

In this post, we will understand the difference between SQL and T-SQL.SQLIt is a non-procedural language.Relational databases use SQL.It stands for structured query language.It uses query to view and manipulate data.DML and DDL operations are used- Data manipulation language, and data definition language.It is considered as an open-source language.It helps in the manipulation of data and data controlling.Transfer of data happens one by one when SQL is used.T-SQLIt is a Microsoft product.It is known as Transact Structure Query language.It gives a high degree of control to the developers/programmers.It works its best, and provides good performance with Microsoft SQL server.It is ... Read More