In SQL Server, a built-in function named DATEADD() is used to add days to a date. However, Postgres doesn’t support the DATEADD() function. In Postgres, the functionality of the DATEADD() function can be achieved via the “+” operator. The plus "+" operator in Postgres allows us to add specific days to a date field.

How to add days to a date field will be explained in this Postgres blog using Practical examples. So, let’s get started!

Postgres Add Days to Date

To add a specific number of days to a date, users must use the plus “+” operator as follows:

date_field + num_of_days;

The plus operator will retrieve a new date representing the original date plus the specified number of days.

Example 1: Find the Current Date

Let’s first find today’s date using the below-provided command:

SELECT CURRENT_DATE;

The output snippet shows that the current date is “2022-12-22”.

Example 2: Add Five Days to the Current Date

Use the “+” operator to add 5 days to the current date:

SELECT CURRENT_DATE + 5;

The output snippet shows that five days have been added to the current date successfully.

Example 3: Add INTERVAL to the Current Date

You can also add the days to the date using the INTERVAL data type:

SELECT CURRENT_DATE + INTERVAL '3 days';

Three days have been added to the current date successfully.

Example 4: Add 3 Days to a Specific Date Field

You can add days to any specific date field as follows:

SELECT DATE '2022-12-12' + 3;

The output snippet shows that three days have been added to the input date field.

Example 5: Add a Negative Number(Days) to a Specific Date Field

Specifying a negative value will subtract the specified number of days from the given date field:

SELECT DATE '2022-12-12' + INTERVAL '-3 days';

Three days have been subtracted from the given date field. Therefore, to add a negative number to the date field, users must use the “-” operator instead of the “+” operator:

SELECT DATE '2022-12-12' - INTERVAL '-3 days';

The output snippet shows that the negative days have been added to the specified date field successfully.

Example 6: Use + Operator on Table’s Data

Let’s consider a practical scenario to understand the working of the “+” operator in a better way:

CREATE TABLE cnic (
issued_date DATE,
valid_until INTERVAL);

A sample table named “cnic” is created with two columns: issued_date and valid_until. Let’s run the below-provided query to insert a couple of records in the “cnic” table:

INSERT INTO cnic(issued_date, valid_until) 
VALUES ('2015-01-18', INTERVAL '1825 days'),
('2018-11-01', INTERVAL '1825 days');

Let’s query the data of “cnic” table using the below-provided command:

SELECT * FROM cnic;

Now we will use the “+” operator to find the expiry date of the cnic:

SELECT issued_date + valid_until as expiry_date
FROM cnic;

This way, you can add any particular day(s) to a date field in Postgres.

Conclusion

Postgres allows us to add a certain number of days to a date field using the plus “+” operator. In other databases like SQL Server, MySQL, etc., a built-in function named DATEADD() is used to add days to a date. However, Postgres doesn’t support the DATEADD() function. In Postgres, the functionality of the DATEADD() function can be achieved via the “+” operator. This Post explained how to add a certain number of days to a date in Postgres via several examples.