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In database management systems (DBMS), super keys are an essential concept used to identify unique records in a table. A super key is a set of one or more than one attribute that can uniquely identify a record in a table. In this article, we will explore the number of possible super keys in a database and their significance. What is a Super Key? A super key is a group of attributes in a table that can identify each row in that table uniquely. It's different from primary and candidate keys because only the smallest possible super keys can be ... Read More
You should consider the needs of the applications during designing a database. Object databases offer a unique approach to database design that can be beneficial in certain situations. In this article, we will discuss the conceptual design of object databases. Object database design Object-Oriented Model is process of representing real-world entities as objects in computer programs. It is fundamental aspect of Object Database Conceptual Design. Object-oriented modeling is more flexible and dynamic than traditional relational model. It enables developers to model complex relationships between objects more efficiently. Object-oriented modeling allows for inheritance, encapsulation, and polymorphism. It is easier to maintain ... Read More
DBMS supports object-oriented data. It ensures direct correspondence between real-world objects and their representations in the database. This correspondence ensures that objects retain their integrity and identity. It enables easy identification and manipulation. Object Data Management System (ODMS) assigns unique identity to each independent object stored in the database. This unique identity is implemented through a system-generated object identifier (OID). This OID serves as distinct value assigned to each object by the system. It is not visible to external users. However it is internally utilized by the system to ensure the unique identification of each object and to establish and ... Read More
In DBMS, there are object-relational features that combine elements of object databases with SQL. SQL language is used for relational databases, and it has evolved over time. In the latest standard called SQL:2008, object features have been incorporated, although not all commercial DBMSs have implemented these features yet. Object-relational model refers to the combination of the relational model and object database enhancements. SQL has undergone revisions to include features related to XML as well. Here are some of the object database features included in SQL: Type Constructors New type constructors have been added to specify complex objects. For example, the ... Read More
Offset-Fetch is feature in MS SQL Server. It helps to retrieve subset of rows from result set. It consists of two components: OFFSET and FETCH. The OFFSET clause specifies the number of rows to skip from the beginning of the result set. FETCH clause determines the number of rows to retrieve. Syntax SELECT column1, column2, ... FROM table ORDER BY column OFFSET {integer_value} {ROWS | ROWS ONLY} FETCH {FIRST | NEXT} {integer_value} {ROWS | ROWS ONLY} ONLY; Explanation of Syntax SELECT column1, column2, ...: Specifies the columns to be selected from the table. FROM table Specifies the table from ... Read More
OLAP (Online Analytical Processing) is data processing technique. It is used to query and analyze data. It analyze data in real time from multiple sources. In 1993, EF Codd introduced 12 rules for the relational database model for OLAP systems. These rules are known as "Codd’s rules". These rules serve as a guideline for the design and development of OLAP systems. In this article, we will explore these 12 rules developed by Codd. Codd’s rules These are 12 rules for OLAP systems, as proposed by E.F. Codd − Multidimensional Conceptual View OLAP system should provide multidimensional conceptual view of ... Read More
Online Analytical Processing Server (OLAP) is used to enable users to perform analysis on information retrieved from multiple database systems concurrently. It operates on a multidimensional data model. Users can write query data across multiple dimensions, such as location, time, and categories (e.g., Hyderabad-> 2017 -> Sales data). In OLAP, databases are organized into one or more cubes. These cubes are known as Hyper-cubes and represent a multi-dimensional array of data. Each cell within the array corresponds to specific combination of dimension values. The dimensions define the characteristics or attributes. Data can be sliced and diced for analysis by attributes. ... Read More
On-Line Transaction Processing (OLTP) System is a type of computer system that helps manage transaction-related tasks. These systems are made to quickly handle transactions and queries on the internet. For instance, supermarket's POS (point of sale) system is an example of an OLTP system. Almost every industry nowadays uses OLTP systems to keep track of their transactional data. OLTP systems mainly focus on entering, storing, and retrieving data, which includes daily operations like purchasing, manufacturing, payroll, accounting, etc. Many users use these systems for short transactions. They support simple database queries, which makes it easier for users to get ... Read More
Retrieval and Update Operations When we work with files, we usually do two types of operations: retrieval and update. Retrieval operations help us find specific records in the file and look at their data. Update operations change the file by adding, removing, or modifying records. Selection Conditions To do either operation, we may need to specify a condition that the records must meet. For example, we might want to retrieve all the records where the salary is greater than or equal to $30, 000. This is called a selection condition. Selection conditions can be simple or complex. A simple condition ... Read More
Cassandra is a distributed NoSQL database system. It offers high scalability, availability, and fault-tolerance. It uses a decentralized architecture, where data is distributed across multiple nodes, and provides several operations to manipulate data. In this article, we will discuss operations on tables in Cassandra. Creating Tables The first operation in Cassandra is to create a table. A table is defined by set of columns. Each column has name, data type, and an optional value. To create a table, you need to specify the keyspace. It is namespace that defines the replication strategy, and the table name. You also need to ... Read More