Arithmetic expressions

You already know quite a bit about data types and literals in SQL. It's time to dig deeper and discuss arithmetic and logic expressions. As a cool bonus, we'll teach you how to make a simple calculator with this knowledge!

Arithmetic

If you remember a bit of school math, arithmetic expressions in SQL will look familiar to you. We can also perform mathematical calculations on our data.

The basic set of arithmetic operators supported in SQL is the following:

• - unary minus that changes the sign of a value;

SELECT -2;
> -2

• * multiplication;
• / division;
• % modulo that returns the remainder of integer division;

SELECT 20*15;
> 300
SELECT 3/5;
> 0.60
SELECT 18%4;
> 2

• + addition;
• - subtraction.

SELECT 30+234;
> 264
SELECT 3-5;
> -2

SQL supports the common rules of operator precedence. In the list above operators are sorted in descending priority. SQL also supports brackets to make an operator take priority over any other operation.

Calculator

After reading this topic, you can now use SQL when you do not have a calculator at hand! This sounds like quite a lifehack. Moreover, now you know how to process strings. Very impressive!

In SQL you can select not only a literal but an arithmetic expression, as well. Let's provide a template for a simple SQL query that extracts an expression:

SELECT expression;

The statement consists of three parts: the keyword SELECT, the expression we want to evaluate, and a semicolon that defines the end of the query.

For example, the code below evaluates the expression (2+2)*15.

SELECT (2+2)*15;

The query evaluation result is 60.

Summary

As you can see, with SQL you can handle arithmetic expressions. SQL allows you to work with operators such as +, -, *, /, %. Thanks to this, you can even write a calculator!

Well, this covers a lot. Let's now move on to the practical tasks?