How DAY works in SQL? Best DAY examples

How DAY works in SQL? Best DAY examples

When working with SQL, dealing with dates and times is an essential skill. One common task is extracting or manipulating days from date values, which is where the DAY function comes into play. In this article, I’ll walk you through how DAY works in SQL, showcasing examples and practical use cases.

Understanding the DAY Function in SQL

The DAY function in SQL is a built-in function that extracts the day part from a given date. This means if you have a date like ‘2024-06-15’, the DAY function will return ’15’. It can be incredibly useful when working with reports, filtering records, or performing date-based calculations.

Basic Syntax of DAY in SQL

The syntax of the DAY function is quite simple:

SELECT DAY(date_column) FROM table_name;

Or, if you want to use it with a specific date:

SELECT DAY('2024-06-15');

This query will return:

15

Examples of Using DAY in SQL

Extracting the Day from a Date Column

If you have a table named orders with a column order_date, you can retrieve the day of each order like this:

SELECT order_id, order_date, DAY(order_date) AS day_of_order
FROM orders;

This query will output data like:

order_id order_date day_of_order
101 2024-05-12 12
102 2024-06-03 3

Filtering Records by a Specific Day

Let’s say you want to find all orders placed on the 15th day of any month. You can use the DAY function in a WHERE clause:

SELECT * FROM orders
WHERE DAY(order_date) = 15;

Common Use Cases for the DAY Function

  • Generating date-based reports – Useful for pulling data grouped by days.
  • Filtering records – Finding data entries that happened on a specific day of the month.
  • Sorting and grouping – Organizing data based on day values.
  • Calculating time differences – Extracting day values for further calculations.

DAY Function with Different SQL Engines

The DAY function works slightly differently depending on the SQL engine you’re using. Here’s how it is implemented in some popular databases:

  1. MySQL: SELECT DAY('2024-06-15');
  2. SQL Server: SELECT DAY('2024-06-15');
  3. PostgreSQL: SELECT EXTRACT(DAY FROM TIMESTAMP '2024-06-15');
  4. Oracle: SELECT EXTRACT(DAY FROM DATE '2024-06-15') FROM dual;

Conclusion

Now you know how the DAY function works in SQL and how it can enhance your date-related queries. Whether you’re extracting, filtering, or sorting, this function plays a key role in handling date values effectively. Try incorporating it into your queries and see how it simplifies your SQL tasks!

 

Other interesting article:

How MONTH works in SQL? Best MONTH examples