Add note about "parsing" NSDate's from SQL

Understanding-the-Photos-database.md

@@ -40,6 +40,14 @@ Dates & times in the database are stored as a MacOS time value which is the numb
 td = (datetime(2001, 1, 1, 0, 0) - datetime(1970, 1, 1, 0, 0)).total_seconds()
 ```
 
+The `NSDate` values can also be "parsed" directly with [sqlite's `datetime` function](https://sqlite.org/lang_datefunc.html#modifiers), e.g.
+
+```sql
+datetime(ZCREATIONDATE, 'unixepoch', '31 years')
+```
+
+---
+
 Additional details about the Photos 5 database structure are [here](https://github.com/RhetTbull/osxphotos/wiki/Photos-version-5-database).
 
 Additional details about the Photos 4 database structure are [here](https://github.com/RhetTbull/osxphotos/wiki/Photos-version-4-database).