One such task includes rounding numbers. Rounding down, also known as flooring, refers to a common mathematical operation that involves adjusting a numerical value to the next nearest lower whole number or a specific decimal place.

Rounding down typically involves truncating the decimal part of a given number or moving towards zero on the basic number line. A common use of flooring or rounding down is simplifying a number to a whole number or specific precision.

Let us explore how to round down in various SQL databases.

## Round Down in MySQL/SQL Server

To round down in MySQL and SQL Server, we can use the floor() function to floor a number to the nearest integer of a given decimal value.

An example usage is as follows:

SELECT FLOOR(9.3);

SELECT FLOOR(-4.6);

The previous example demonstrate how to use the “floor” function in MySQL to floor various numerical values.

The first example should round 7.8 to 7 and the second example should round 9.3 to 9.

NOTE: When we floor a negative number, the “floor” function rounds the number to a more negative integer.

## Round Down in PostgreSQL

Like MySQL, PostgreSQL also provides the FLOOR() function to floor a given number to the nearest integer or decimal.

SELECT FLOOR(7.8);

SELECT FLOOR(9.3);

SELECT FLOOR(-4.6);

This should return similar results as the MySQL example.

We can also use the CAST() function in PostgreSQL to floor a given value. Examples are as follows:

SELECT CAST(9.3 AS DECIMAL(5, 0));

SELECT CAST(-4.6 AS DECIMAL(5, 0));

In this case, we use the cast() function so specify the number of decimal places for which we wish to round. In our case, we round it to 0 decimal places.

## Round Down in Oracle

Oracle provides us the FLOOR() function to round down to the nearest integer. An example usage is as follows:

SELECT FLOOR(9.3) FROM DUAL;

SELECT FLOOR(-4.6) FROM DUAL;

As with other databases, FLOOR() in Oracle rounds the numbers down to the nearest integer or a lower integer for negative numbers.

## Conclusion

In this short post, we learned how to round down, also known as flooring, in SQL databases using the floor() or cast() functions whenever applicable.