Found 118 Articles for SQL

When it comes to storing character data in a database, there are two main types of fields you can use in SQL: CHAR and VARCHAR. While both can be used to store character data, they have some important differences that you should be aware of in order to make the best use of them in your database design. Length and Storage The first major difference between CHAR and VARCHAR is the way they store data. CHAR is a fixed-length field, which means that every record that uses it takes up the same amount of space. For example, if you have ... Read More

Two Phase Locking (2PL) is a fundamental technique used in database management systems to ensure the consistency and isolation of concurrent transactions. In this article, we will discuss the three categories of 2PL: strict 2PL, rigorous 2PL, and conservative 2PL, and explain how they differ in terms of their locking protocols. We will also provide code examples with explanations to illustrate how these categories can be implemented in practice. Introduction to Two-Phase Locking Before diving into the specific categories of 2PL, let's first review the basics of 2PL. Two Phase Locking is a technique used to control concurrent access to ... Read More

Introduction In machine learning, the data and its quality are one of the most critical parameters affecting the performance and other parameters while training and deploying the machine learning model. It is assumed that if good-quality data is provided to a poorly performing machine learning algorithm, there is a high chance of better performance than ever from the algorithm and vice versa. In this article, we will discuss the two common types of data: structured and unstructured data. Here we will discuss their definitions and the core intuition behind them, followed by some other meaningful discussion. Knowledge about these key ... Read More

Introduction to the CAST Function in Cassandra Cassandra is a highly scalable and distributed NoSQL database that is well-suited for storing and managing large amounts of data. One of the key features of Cassandra is its powerful query language, CQL (Cassandra Query Language), which allows you to easily retrieve and manipulate data stored in Cassandra. One useful function in CQL is the CAST function, which allows you to change the data type of a column or expression. This function is particularly useful when you need to perform calculations or comparisons on data that have different data types. In this article, ... Read More

Cascadeless in DBMS: Understanding and Implementing the Concept A database management system (DBMS) is a software that is used to store, organize, and manage data in a structured manner. One of the key concepts in DBMS is cascading, which refers to the automatic propagation of changes made to the data in one table to the related data in other tables. While cascading can be convenient in many cases, it can also lead to unintended consequences, such as data loss. To mitigate this, many DBMSs allow for the use of cascadeless operations, which prevent cascading from taking place. In this article, ... Read More

In the field of database management systems (DBMS), a candidate key is a set of one or more columns that can uniquely identify a row within a table. A candidate key is also known as a "unique identifier" or "primary key." In this article, we will discuss the importance of candidate keys in DBMS and how they are used to maintain the integrity and consistency of a database. What is a Candidate Key? A candidate key is a set of one or more columns that can be used to uniquely identify a row within a table. In other words, no ... Read More

Introduction In a database management system (DBMS), the scheduler is responsible for managing the execution of concurrent transactions. The scheduler uses a schedule, which is a sequence of actions that the DBMS must execute, to ensure that the system remains in a consistent state and that concurrent transactions do not interfere with each other. There are two types of schedules: serial schedules and non-serial schedules. In this article, we will discuss the calculation of both types of schedules in a DBMS. Serial Schedules A serial schedule is a schedule in which all transactions are executed one after another, without any ... Read More

Introduction A data model is a blueprint that represents the organization of data and the relationships between different data entities. It is an essential component of any software system as it defines how data is stored, accessed, and modified. In this article, we will explore the building blocks of a data model and how they work together to form a cohesive whole. Data Entities The first building block of a data model is data entities, which represent the objects or concepts that are relevant to the system. For example, in an e-commerce system, data entities might include products, customers, orders, ... Read More

A data warehouse is a central repository of integrated data that is used for reporting and analysis. It stores large amounts of historical and current data and enables fast query performance for analytical purposes. A data warehouse can be used to support business decision-making, improve operational efficiency, and gain a competitive edge. In this article, we will discuss the process of building a data warehouse from scratch. Understanding the Requirements for a Data Warehouse Before starting the design and construction of a data warehouse, it is important to understand the business requirements and the type of data that will be ... Read More

Data was previously stored in relational data management systems when Hadoop and big data concepts were not available. After introducing Big Data concepts, it was essential to store the data more concisely and efficiently. However all data stored in the related data management system needs to be transferred to the Hadoop archive. With Sqoop, we can transfer this amount of personal data. Sqoop transfers data from a related database management system to a Hadoop server. Thus, it facilitates the transfer of large volumes of data from one source to another. Here are the basic features of Sqoop − Sqoop ... Read More