Multidimensional databases are used mostly for OLAP (online analytical processing) and data warehousing. They can be used to show multiple dimensions of data to users .A multidimensional database is created from multiple relational databases. While relational databases allow users to access data in the form of queries, the multidimensional databases allow users to ask analytical questions related to business or market trends.The multidimensional databases uses MOLAP (multidimensional online analytical processing) to access its data. They allow the users to quickly get answers to their requests by generating and analysing the data rather quickly.The data in multidimensional databases is stored in ... Read More

Mobile databases are separate from the main database and can easily be transported to various places. Even though they are not connected to the main database, they can still communicate with the database to share and exchange data.The mobile database includes the following components −The main system database that stores all the data and is linked to the mobile database.The mobile database that allows users to view information even while on the move. It shares information with the main database.The device that uses the mobile database to access data. This device can be a mobile phone, laptop etc.A communication link ... Read More

Open source databases are those databases who have an open source code i.e anyone may view the code, study it or even modify it. Open source databases could be relational (SQL) or non relational (NoSQL).Why use Open Source Databases?It is quite expensive to create and maintain a database for any company. A huge chunk of the total software expenditure is used to handle databases. So, it is feasible to switch to low cost open source databases. This saves companies a lot of money in the long run.Open Source Databases in useThere many different open source databases in the market. All ... Read More

The date and time functions in DBMS are quite useful to manipulate and store values related to date and time.The different date and time functions are as follows −ADDDATE(DATE, DAYS)The numbers of days in integer form (DAYS) is added to the specified date. This is the value returned by the function. For example −sql> SELECT ADDDATE('2018-08-01', 31); +---------------------------------------------------------+ | DATE_ADD('2018-08-01', INTERVAL 31 DAY)                 | +---------------------------------------------------------+ | 2018-09-01                                             | +---------------------------------------------------------+ 1 ... Read More

The select statement is used to get the required data from the database according to the conditions, if any. This data is returned in the form of a table.The basic syntax of the select statement is −Select column 1, column 2 ... column N From table_nameAn example of the select statement is −Student_NumberStudent_NameStudent_PhoneStudent_MarksStudent_MajorSubject1Andrew661592728495Literature2Sara658365486565Maths3Harry464756746348Literature4Sally653783708430Literature5Anne745733773288MathsQuery −Select Student_Name From StudentThis query yields the following result −Student_NameAndrewSaraHarrySallyAnneClauses in Select statementThe example of select statement given above is quite simple and not that useful in practice. So, there are many other clauses associated with select statement that make it more meaningful. Some of these are ... Read More

The ANSI-SPARC database architecture is the basis of most of the modern databases.The three levels present in this architecture are Physical level, Conceptual level and External level.The details of these levels are as follows −Physical LevelThis is the lowest level in the three level architecture. It is also known as the internal level. The physical level describes how data is actually stored in the database. In the lowest level, this data is stored in the external hard drives in the form of bits and at a little high level, it can be said that the data is stored in files ... Read More

An Object relational model is a combination of a Object oriented database model and a Relational database model. So, it supports objects, classes, inheritance etc. just like Object Oriented models and has support for data types, tabular structures etc. like Relational data model.One of the major goals of Object relational data model is to close the gap between relational databases and the object oriented practises frequently used in many programming languages such as C++, C#, Java etc.History of Object Relational Data ModelBoth Relational data models and Object oriented data models are very useful. But it was felt that they both ... Read More

Object oriented data model is based upon real world situations. These situations are represented as objects, with different attributes. All these object have multiple relationships between them.Elements of Object oriented data modelObjectsThe real world entities and situations are represented as objects in the Object oriented database model.Attributes and MethodEvery object has certain characteristics. These are represented using Attributes. The behaviour of the objects is represented using Methods.ClassSimilar attributes and methods are grouped together using a class. An object can be called as an instance of the class.InheritanceA new class can be derived from the original class. The derived class contains ... Read More

Database Management System is quite useful compared to the file based management system. However, it does have some disadvantages. Some of those are as follows −More CostlyCreating and managing a database is quite costly. High cost software and hardware is required for the database. Also highly trained staff is required to handle the database and it also needs continuous maintenance. All of these ends up making a database quite a costly venture.High ComplexityA Database Management System is quite complex as it involves creating, modifying and editing a database. Consequently, the people who handle a database or work with it need ... Read More

The systems that are used to organize and maintain data files are known as file based data systems. These file systems are used to handle a single or multiple files and are not very efficient. FunctionalitiesThe functionalities of a File-based Data Management System are as follows −A file based system helps in basic data management for any user.The data stored in the file based system should remain consistent. Any transactions done in the file based system should not alter the consistency property. The file based system should not allow any illegal or potentially hazardous operations to occur on the data.The file based ... Read More