PostgreSQL FLOOR() Function

PostgreSQL FLOOR() Function

The PostgreSQL FLOOR() function is used to return the largest integer value that is less than or equal to a given number. This function is essential for rounding down numerical values to the nearest integer.

Syntax

FLOOR(number)

The FLOOR() function has the following component:

  • number: The number to be rounded down.

Example PostgreSQL FLOOR() Queries

Let's look at some examples of PostgreSQL FLOOR() function queries:

1. Basic FLOOR() Example

SELECT FLOOR(4.7) AS rounded_value;

This query returns the largest integer value less than or equal to 4.7, which is 4.

2. FLOOR() with Column Values

SELECT value, FLOOR(value) AS rounded_value
FROM numbers;

This query retrieves the value and its rounded-down value from the numbers table.

3. FLOOR() with Negative Values

SELECT value, FLOOR(value) AS rounded_value
FROM numbers
WHERE value < 0;

This query retrieves the value and its rounded-down value from the numbers table where the value is negative.

Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the FLOOR() function to retrieve the rounded-down values.

Step 1: Creating a Table

This step involves creating a new table named numbers to store numerical data.

CREATE TABLE numbers (
    id SERIAL PRIMARY KEY,
    value NUMERIC
);

In this example, we create a table named numbers with columns for id and value.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the numbers table.

INSERT INTO numbers (value)
VALUES (4.7),
       (2.3),
       (-3.8),
       (7.9);

Here, we insert data into the numbers table.

Step 3: Using the FLOOR() Function

This step involves using the FLOOR() function to retrieve the rounded-down values from the numbers table.

-- Basic FLOOR()
SELECT value, FLOOR(value) AS rounded_value
FROM numbers;

-- FLOOR() with Negative Values
SELECT value, FLOOR(value) AS rounded_value
FROM numbers
WHERE value < 0;

These queries demonstrate how to use the FLOOR() function to retrieve the rounded-down values from the numbers table, including basic usage and handling negative values.

Conclusion

The PostgreSQL FLOOR() function is a fundamental tool for rounding down numerical values to the nearest integer. Understanding how to use the FLOOR() function and its syntax is essential for effective data retrieval and manipulation in PostgreSQL databases.