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# how to calculate age formula SQL

to calculate age formula SQL could be easy all we need is a birth date, you need to know their date of birth. Therefore, when working in SQL Server or PostgreSQL, we need to have a date of birth in our client or employee table.

Therefore, I will show you how to calculate age and years using SQL, in another article we will work with date format. For now, let’s focus on calculating birth dates.

Índice

## Calculate age formula SQL Server

In SQL Server, you can also calculate a person’s age from their date of birth using the DATEDIFF function to get the difference between the current date and the date of birth in years.

Here is an example:

``````SELECT DATEDIFF(YEAR, date_of_birth, GETDATE()) AS 'Age'
FROM persons_table;
``````

In this example, the DATEDIFF function is used to calculate the difference in years between the person’s date of birth and the current date (obtained using the GETDATE() function).

The query returns the result of the date difference, which is the person’s age.

## Create an age’s calculated field

In SQL Server, you can create a calculated field to calculate a person’s age from their date of birth. To do this, you can use the DATEDIFF function to get the difference between the current date and the date of birth in years.

Here’s how to create a calculated age field in an existing table:

``````ALTER TABLE persons_table
ADD age AS DATEDIFF(YEAR, date_of_birth, GETDATE());
``````

In this example, the ALTER TABLE statement is used to add a calculated field called «age» to the «persons_table» table. The DATEDIFF function is used to calculate the difference in years between the person’s date of birth and the current date (obtained using the GETDATE() function). The AS keyword is used to indicate that «age» is a calculated field and not a physical data column.

Once the calculated field is created, you can select it in queries as if it were a physical data column:

``````SELECT name, age FROM persons_table;
``````

In this example, the name and age of all people in the «persons_table» table are selected, with age being returned as a calculated field.

## How to calculate age in PostgreSQL

In PostgreSQL, you can calculate a person’s age from their date of birth using the AGE function, which takes the birthdate and the current date as arguments. Here is an example query using pgAdmin to create a query using the age function:

``````SELECT AGE(fecha_nacimiento) AS "age"
FROM tabla_personas;
``````

In this example, the AGE function is used to calculate the age of the person based on their date of birth. The query returns the result of the AGE function, which is an interval of time representing the person’s age in years, months, and days.

## Conclusion

calculate the age of a person or an inventory item, it may vary by management system but essentially it is one of the most basic calculations that we can perform in management systems.

thanks see you soon!!