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SQL is null – SQL is not null

In this article, we’re going to see how to test null values in an SQL database. 1. What is a NULL Value? Basically, a field with a NULL value in a SQL table is a field without value. When creating a table, we can mark a column that accepts null values when inserting data into the table. A null value ...

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SQL UNION Operator

In this article, we will explain the SQL UNION Operator through examples. 1. Introduction SQL UNION operator combines results from two select statements into a single result which includes all unique rows. UNION ALL includes duplicated rows in the combined result. The syntax is as the following: SELECT_QUERY_1 UNION [ALL] SELECT_QUERY_2 Note, the two SELECT queries must meet the following ...

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SQL Server Versions

In this article, we’re going to see several Microsoft SQL Server versions and editions and how to identify them. 1. Introduction On MSSQL Server we need to determine the version and edition to troubleshoot some issues or to know if feature support is available. To do that, MSSQL Server introduces some procedures to identify the version and edition which we’re ...

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SQL Count Function

In this article, we will discuss the COUNT function in SQL, different ways of using it, and how to combine it with other keywords like GROUP BY and HAVING. 1. Introduction Many times, the information we want from a database table is not available in a single row but in a group of rows or in the result of a ...

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SQL Tutorial for Beginners

This is an SQL tutorial for beginners. We will discuss what is SQL and what it is used for. You can also check this tutorial in the following video: SQL Tutorial for Beginners – video 1. Why to Learn SQL SQL stands for Structured Query Language and is a standard language for accessing and manipulating databases. Although SQL is an ...

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SQL Server 2019: Overview and Installation

1. Introduction In this tutorial, we will see some new and key features of SQL Server 2019 and we will write a small example to help you get started. 2. What’s new in SQL Server 2019 2.1 Intelligent Query Processing Enhancements This is a set of enhancements that improves Query Optimizer. Query Optimizer is a component inside SQL Server that ...

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SQL GROUP BY Statement

1. Introduction In this article, we will look at the Group by Clause. We can use the Group By clause with all the databases that support SQL. We will see how we use Group BY in the MySQL database. 2. SQL Group By Clause The Group By is a clause that clumps data into groups based on a shared value. ...

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SQL Join Tutorial

In this article, we will discuss JOINs in SQL (Structured Query Language), various types of JOINs, and their syntax. We will also run SELECT queries using different types of JOINs on data in sample tables and view the result sets. You can also check this tutorial in the following video: SQL Join Tutorial – video 1. Introduction In real-world applications, ...

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SQL Injection

This article will look at what SQL injection means and a few ways to prevent it. 1. What is SQL injection? SQL injection is a security problem in SQL. It is one of the most common hacking techniques for any database. An SQL injection happens when we try to receive user input from the user interface, such as a username. Instead ...

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PostgreSQL with Node.js and Express.js

Hello in this tutorial, we will understand how to create a RESTful API in a Node.js environment running on an Express.js server and using a PostgreSQL database. The tutorial will cover the CRUD operations on the API which will execute the corresponding database commands. 1. Introduction RESTful API stands for the standard web service interface used by the applications to ...

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