Sql Operators

Agnieszka Kozubek-Krycuń

NULLs and Handling Missing Data in SQL

Handling missing data (i.e. NULLs) in SQL can be challenging. NULLs can pose a lot of traps, especially if you don’t understand how they work. In this article, we’ll talk about dealing with NULL in SQL. We’ll also explain how to avoid common mistakes when working with NULLs. Having missing data in your database is an unavoidable reality of life. There are many reasons why you may have missing data in your database: the complete data isn’t yet available, users provide incomplete information, changes to the database schema, database malfunctions, human error, and more.

Ignacio L. Bisso

The SQL EXISTS Operator

Using the SQL EXISTS clause allows us to create complex queries in a simple way. Learn the pros and cons of the EXISTS operator in this article. In SQL, the EXISTS operator helps us create logical conditions in our queries. Essentially, it checks if there are any rows in a subquery. We’ll show you EXISTS syntax, provide some usage examples, and then give you several exercises to practice on.

Maria Durkin

The SQL BETWEEN Operator

SQL comparison operators are essential tools for filtering data in database queries. Among these operators, the BETWEEN operator stands out as an important tool for specifying ranges inside datasets. SQL comparison operators, such as BETWEEN, are useful for filtering data in database queries. The BETWEEN operator allows you to select rows within a given range, making it ideal for tasks like segmenting an audience by age ranges, identifying thresholds for items between certain quantities, or categorizing performance based on exam scores.

Radu Gheorghiu

SQL IN Operator

Why do you need to know SQL IN? Find out what you can do with this small but powerful operator. The IN operator is a fundamental tool in SQL, enabling data analysts and developers to filter and retrieve specific subsets of data from databases. While its basic usage may seem straightforward, mastering the nuances and advanced applications of the SQL IN operator can greatly enhance your SQL skills and lead to more powerful and optimized queries.

Dominika Florczykowska

What Does a Double Colon Operator in PostgreSQL Do?

The double colon operator :: in PostgreSQL is a synonym for CAST, which converts a value into a different data type.  If you are curious about the details , read on! Have you ever seen a double colon (::) operator in someone’s PostgreSQL code? It would look something like this: SELECT '2022-09-02'::date; This code converts the text '2022-09-02' to a date datatype. As mentioned above, the double colon replaces the CAST operator.

Andrew Bone

How the Division Operator Works in SQL

The division operator in SQL is used to divide one expression or number by another. This article will show you exactly how to use it and common mistakes to avoid along the way. The best way to practice SQL is our interactive SQL Practice track. It contains over 600 hands-on exercises that conver varios SQL topics, from simple one-table queries, through JOINs, to complex topics like subqueries. It lets you train your SQL skills on real business examples.

James Wondrasek

How to Use Comparison Operators with NULLs in SQL

The SQL NULL value serves a special purpose. It also comes with counterintuitive behaviors that can trip up SQL beginners or even experienced programmers. Learn how to avoid these problems when you use NULL with comparison operators. This article is going to help you master best practices for crafting SQL queries that work with NULL values and use comparison operators ( =, <>, <, > ) – which, if you have written any SQL queries before, you know is just about every query you will ever write!

Andrew Bone

Using AND, OR, and NOT Operators in SQL

AND, OR, and NOT are important logical operators in SQL. They help you combine the conditions used to filter records. They are most commonly used in conjunction with the WHERE or HAVING clauses. Furthermore, this topic is a pretty common SQL job interview question. To help you completely understand these operators, I’ll take you through some examples, fully explaining the syntax and purpose of each. Practicing using examples like these is one of the best methods for learning SQL.

Dorota Wdzięczna

How to Use LIKE in SQL: SQL Pattern Matching

SQL pattern matching is a very important and useful ability. In this article, we look at how you can perform it using LIKE in SQL. SQL Pattern matching is a very simple concept. It allows you to search strings and substrings and find certain characters or groups of characters. Apart from SQL, this operation can be performed in many other programming languages. In this article, we’ll examine how you can use LIKE in SQL to search substrings.