I really think that cleaning up data before it goes to the database should be done at another tier in your system. Other languages and tools have much much better...

My thought would be to pre-allocate periods, using the ISO half open interval model. Then each client would be given one or more periods. The the unallocated periods would...

>> First off Joe, the schema has already been built. <<

It was already built, then why didn't you post the DDL for it? We can't read your mind....

You don't seem to understand that dates are not kept in strings in SQL. That was COBOL, so doing string operations to pick out the the year, month and date...