How to Round Numbers in SQL

Problem:

You want to round a number to a specific number of decimal places in SQL.

Example:

Our database has a table named product with data in the following columns: id, name, and price_net.

Suppose there’s a tax of 24% on each product, and you’d like to compute the gross price of each item (i.e., after taxes) and round the value to two decimal places.

Solution:

SELECT 
  id, 
  ROUND(price_net * 1.24, 2) as price_gross
FROM product;

This query returns the gross price rounded to two decimal places:

Discussion:

If you’d like to round a floating-point number to a specific number of decimal places in SQL, use the ROUND() function. The first argument of this function is the column whose values you want to round; the second argument is optional and denotes the number of places to which you want to round. By default, if you don’t specify the second argument, the function rounds to the nearest integer.

In this example, we won’t specify the number of places to which we want to round the column:

SELECT 
  id, 
  ROUND(price_net * 1.24) as price_gross
FROM product;

And here’s the corresponding result:

Note that the rounding is done according to mathematical rules of rounding: the number is rounded to the nearest integer. 2.90 for the product with ID of 1 is rounded up to 3, but 0.47 for the product with ID of 3 is rounded down to 0.