# How the FLOOR() function works in Mariadb?

The `FLOOR()`

function is a mathematical function that returns the largest integer value that is less than or equal to a given number.

The `FLOOR()`

function is a mathematical function that returns the largest integer value that is less than or equal to a given number. It can be used to round down a number to the nearest integer, or to truncate the decimal part of a number.

## Syntax

The syntax of the `FLOOR()`

function is as follows:

```
FLOOR(X)
```

The function takes one argument:

`X`

is the number to be rounded down.

The function returns an integer value that is the result of rounding down `X`

. If `X`

is `NULL`

, the function returns `NULL`

.

## Examples

### Example 1: Using FLOOR() function with positive numbers

The following example shows how to use the `FLOOR()`

function with positive numbers:

```
SELECT FLOOR(1.5), FLOOR(3.14), FLOOR(5.99);
```

The function returns the largest integer that is less than or equal to each number.

```
+------------+-------------+-------------+
| FLOOR(1.5) | FLOOR(3.14) | FLOOR(5.99) |
+------------+-------------+-------------+
| 1 | 3 | 5 |
+------------+-------------+-------------+
```

### Example 2: Using FLOOR() function with negative numbers

The following example shows how to use the `FLOOR()`

function with negative numbers:

```
SELECT FLOOR(-1.5), FLOOR(-3.14), FLOOR(-5.99);
```

The function returns the largest integer that is less than or equal to each number.

```
+-------------+--------------+--------------+
| FLOOR(-1.5) | FLOOR(-3.14) | FLOOR(-5.99) |
+-------------+--------------+--------------+
| -2 | -4 | -6 |
+-------------+--------------+--------------+
```

### Example 3: Using FLOOR() function with zero

The following example shows how to use the `FLOOR()`

function with zero:

```
SELECT FLOOR(0);
```

The function returns zero, because zero is the largest integer that is less than or equal to zero.

```
+----------+
| FLOOR(0) |
+----------+
| 0 |
+----------+
```

### Example 4: Using FLOOR() function with NULL

The following example shows how to use the `FLOOR()`

function with NULL:

```
SELECT FLOOR(NULL);
```

The function returns NULL, because NULL is not a valid number.

```
+-------------+
| FLOOR(NULL) |
+-------------+
| NULL |
+-------------+
```

### Example 5: Using FLOOR() function with expressions

The following example shows how to use the `FLOOR()`

function with expressions. Suppose we have a table called `sales`

that has the following data:

```
+----+---------+-------+--------+
| id | product | price | amount |
+----+---------+-------+--------+
| 1 | A | 10.50 | 10 |
| 2 | B | 20.00 | 15 |
| 3 | C | 15.75 | 12 |
| 4 | D | 25.00 | 20 |
| 5 | E | 30.00 | 25 |
+----+---------+-------+--------+
```

We can use the `FLOOR()`

function to calculate the total revenue of each product, by multiplying the price and the amount, and rounding down the result to the nearest integer:

```
SELECT product, price, amount, FLOOR(price * amount) AS revenue
FROM sales;
```

The function returns the revenue of each product as an integer value.

```
+---------+-------+--------+---------+
| product | price | amount | revenue |
+---------+-------+--------+---------+
| A | 10.50 | 10 | 105 |
| B | 20.00 | 15 | 300 |
| C | 15.75 | 12 | 189 |
| D | 25.00 | 20 | 500 |
| E | 30.00 | 25 | 750 |
+---------+-------+--------+---------+
```

## Related Functions

Some of the functions that are related to the `FLOOR()`

function are:

`CEIL()`

: This function returns the smallest integer value that is greater than or equal to a given number. It can be used to round up a number to the nearest integer, or to add one to the integer part of a number. For example,`CEIL(1.5)`

returns 2, and`CEIL(-1.5)`

returns -1.`ROUND()`

: This function returns a number rounded to a specified number of decimal places. It can be used to round a number to a desired precision, or to remove the decimal part of a number. For example,`ROUND(1.567, 2)`

returns 1.57, and`ROUND(1.567, 0)`

returns 2.`TRUNCATE()`

: This function returns a number truncated to a specified number of decimal places. It can be used to remove the fractional part of a number without rounding. For example,`TRUNCATE(1.567, 2)`

returns 1.56, and`TRUNCATE(1.567, 0)`

returns 1.

## Conclusion

The `FLOOR()`

function is a useful mathematical function that can be used to round down a number to the nearest integer, or to truncate the decimal part of a number. It returns the largest integer value that is less than or equal to a given number. It can be used with positive or negative numbers, zero, or NULL. It can also be used with expressions to perform calculations and round down the results.