In SQL and relational databases, NULL values are an important part of managing data and information stored in SQL tables. A NULL value is used as a placeholder for missing values or values that are unknown in a database column or cell. Understanding how to handle NULL values is important for database developers who want to avoid errors and retrieve accurate results when querying a database table. This database development tutorial covers the basics of how to work with NULL values in SQL. Read: Best Online Courses to Learn SQL What is a NULL Value in SQL? In relational databases and RDBMS’, NU ..read more

In SQL, data types help to define the type of value that can be stored in a database cell, or, more specifically, in a column. There are many kinds of data types in SQL and in this database programming and administration tutorial, we will look at each one and learn their syntax, how to use them, when to use them, their use case, and how they differ in specific relation database vendors, such as MySQL, Oracle, PostgreSQL and MS SQL Server. Before we begin, if you prefer to learn in a classroom or online environment, we have a list of the Top Online Courses to Learn SQL to help you get started ..read more

PostgreSQL is one of the world’s most widely used database systems in the world, offering support for not only structured query language (SQL), but JSON as well, making it a great choice for database-driven enterprise applications. In this database programming and database administration tutorial, we discuss what PostgreSQL is, its relation to SQL, and the benefits of working with the hybrid database system. Read: What is MySQL? Overview of PostgreSQL PostgreSQL, like other offshoots of SQL database systems, is often viewed as a database programming language. However, this is a misnomer, as P ..read more

In a previous tutorial, we discussed how to use the SQL SELECT statement to return values from a table. In today’s database programming tutorial, we will learn how to use the SELECT DISTINCT statement to return only distinct – or unique – values from a table. You can read about regular SELECT SQL statements in our tutorial: How to Use the SQL SELECT Statement. SQL SELECT DISTINCT Statement and Syntax The SELECT DISTINCT statement is used for cases where you only want to return values that are unique, distinct, or different from one another. For instance, if you have a table with data containi ..read more