How to Subtract one Value From Another in SQL

Problem:

You want to subtract one numeric value from another in SQL.

Example:

As an example, let’s take the table revenue. It stores information on income and expenses for different months. The table has 4 columns: year, month, income, and expenses.

year	month	income	expenses
2022	June	8600	4300
2022	July	5500	4500
2022	August	9000	7300
2022	September	12000	8000

Let’s calculate the profit for each month. To get the profit value, you need to subtract the expenses from the income.

Solution:

To subtract the expenses from the income, take the two columns and subtract one from another using the standard - subtraction operator. Let’s see the differences between income and expenses for the months included in the table:

 SELECT year, month, income - expenses as profit FROM revenue; Here’s the result: 

year	month	profit
2022	June	4300
2022	July	1000
2022	August	1700
2022	September	4000

Discussion:

The use of subtraction in SQL is not limited to SELECT. It is allowed in other parts of the query, e.g., in WHERE:

 SELECT year, month FROM revenue WHERE income - expenses > 3000;