In a "Date" field, how can one enter an unknow date like 01/00/2012 or 00/00/2012?
These are not valid dates and thus cannot be entered into a field of type date as they would trip FileMaker's interal data validation routines.
"In a "Date" field, how can one enter an unknow date"
If a date is unknown but you know the year, is often used January 1, (in your case: 01/01/2012)
Inserting an unknow date implies the date is know. I must have the exact date or zero place holders. Looks as if the best choice is to leave blank. Thanks for the option.
Might it work to define an additional field of type text for entering such data?
The system can be set up so that updating the date field clears the text field and reports could then display either the actual date or the incomplete date. That gives you the best of both worlds, a true date in a date field and incomplete dates that onlyu record the year or the month and year.
This is what I have done in the past. Sometimes a field for the information that is known and sometimes just a flag in the form of a checkbox to indicate that 06/01/2012 means sometime in June of 2012 or 01/01/2012 means sometime in 2012.
The checkbox does not take up a lot of space and is my preference.
If you are unwilling or unable to enter a valid date that is incorrect, meaning you must leave the field empty if it is not correct, but you still want to use the approximate date in a calculation, there is a solution that I have used for that too. I create three fields: month, day, and year. Enter the parts you know to be true. You can then use merge fields to display the portions of the date you do know in reports (if necessary) or use calculation fields to calculate an approximate date to be used in calculations (if the typical date field is empty). It does seem odd to make three fields, but it removes confusion from users about which part of the date is known and which part is estimated. This was important in a solution for a church one time for baptism dates.
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