Decodes most of the possible formats found in RM4 Date fields of the form Da+nnnnnnnn.x+nnnnnnnn.x .
Does not decode Quaker dates nor will it format in any way other than yyyy-mm-dd.
Queries a sample database containing some example dates; this database also contains the query as a VIEW.
The query could be adapted to integrate with a broader query of a RM4 database by renaming the field reference.
It is a large and complex procedure that would be better suited to being programmed as a function in a custom extension of sqlite or in a calling program.
Download query: DateDecoder.sql
Download example database: RMDateFormats.db3
A fuller interpretation of the Date format has been prepared by romermb and can be found on the Dates sheet of the OpenCalc workbook RootsMagic4DataDefs.ods and summarised on the page Date Formats.