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In this tutorial we will highlight how to make a calculated average age query in a database using SQL. For this tutorial, we suppose we are dealing with a table named ‘Customers’, which has a column of birthdates named ‘BirthDate’.
Calculate Age from Birth Date
First, we need to learn how to calculate an age from a birth date. We can use SQL’s built-in function DATEDIFF for this. Here’s an example:
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SELECT DATEDIFF(year, BirthDate, GETDATE()) as Age FROM Customers |
This command calculates the difference in years between the current date (GETDATE()) and the birth date of Customers.
Calculate Average Age
Now that we can calculate the age of every customer, the next step is to calculate the average. We can use the AVG function in SQL for this. Here’s the complete query:
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SELECT AVG(DATEDIFF(year, BirthDate, GETDATE())) as AverageAge FROM Customers |
The AVG function returns the average value of a numeric column. In this case, we calculated the age of every customer and then averaged it.
Note:
The DATEDIFF function in SQL Server calculates the difference between two dates based on the date part that we specify (in this case, year). It’s important to note that DATEDIFF calculates the difference by subtracting the lesser date part from the greater date part, which may not always result in an exact age calculation. For a more precise age calculation, you could consider calculating the difference based on days and then dividing by 365.25 to account for leap years.
Conclusion
SQL provides powerful built-in functions that allow for complex calculations, such as calculating the average age of customers in a database. By understanding and leveraging these functions, you can manipulate and analyze data effectively to gain valuable insights.