Is it possible to have a date that lacks month or day? I’m trying to create a historical data base of early printed books, many of which can be dated only to a single year or range of years. I can of course use text and format the date so it will sort by the year (or first year in a range), but is there any possibility of using the data type “date” (or creating a new data type based on “date”)?
I’m sorry, that is not possible. If you are using a date field, each cell must contain a specific date, including the year, month and day.
How to record dates depends on what you wish to do with them. If all you want is to record, save, display or print them then ordinary text works fine. If you want to chronologically sort or sequence them, automatically place them on a timeline, compute time offsets (eg. three months earlier) from them, then text alone doesn’t suffice. The ‘Date’ data format allows all of those. That format offers a unique value for each date (Gregorian from when the Pope made that change and continuing forward, Julian dates before that extrapolated back, with Jan 1st, 4713BC Julian as date zero.)
Your problem is that a book just dated “1603” might fit 365 different date values. A solution would be to have both ‘text’ and ‘date’ format fields and some consistent convention — whatever makes sense to YOU — to convert the former to the latter. You might use first or last ‘date’ of the possible range or its midpoint. Or you could use two ‘date’ fields, one each for the start and end of the possible range with their values equal for specific dates. The ‘date’ fields could be hidden, to save screen space, but still be available for sorts, etc. If your text is consistent you could program its automatic conversion per your conventions.
Many thanks for the “two date” suggestion; I suspect that approach will bear fruit. I’ll experiment with various possibilities - possibly two date fields, one with 01/01/1603 and the other with 12/31/1603 (for example, as you suggest).
It is a common practice in the legal world when recording dates to use a text date in the format YYYYMMYY, because many documents have only partial dates, a year or a month and a year. Any missing parts are filled in with zeros. With this format, the date will still sort chronologically.