Average age from date of birth

Hi James, please try this code, it should work. 

SELECT AVG(
  (SELECT
    DATETIME_DIFF( {DateOfBirth - Year{label/DateOfBirth.year}, THIS(YEAR) )
    BY {dataset/your_dataset}
  )
)

the last error message is complaining about missing aggregation so we need to wrap the function to AVG - you had it in your original code.

And I also added the “BY dataset” part. It might not be needed in insights with the primary key from the dataset where the date exists, but it might not work if you would just use it alone (i.e. to display AVG age as a headline) or some other attribute.

The “BY dataset” in the inner metric - in your case please use the identifier of the dataset in your model - will ensure that this metric can be also used alone or with non-key attribute. Technically any Date in GoodData is a separate dimension dataset which can be referenced from other datasets, so by this we are telling the system to use the date in connection with your dataset.