Think about a Parent / Child / GrandChild structure inside a database table schema, or perhaps a much deeper hierarchy. These finding yourself in exactly the same aggregate. One table DAYS looks after a single row daily, and it has a "Date" area. This is actually the root table, or simply a child from the root. No row can be erased within this table.

Within this situation, however complex my table schema appears like, however far within the hierarchy every other table is, can there be any reason every other table would hold to start dating ? value? Can't it rather simply have a FK towards the DAYS table.

I clearly think that the development of these date fields happen not before such datefield exist dads and moms table.

I am now thinking nearly the date part to become relevant, not time part. Unsure if all databases can store these individually. That's maybe relevant, although not truly the primary focus from the question.

Yes, your table can reference the times table, but I wouldn't request for any reason to keep only the Date value. I'd request for any reason introducing this new relation, that will decelerate your database and it has - a minimum of according to your description - no additional value. Consider presenting a table with all of possible integers and referencing that certain all other tables. It's possible, but makes very little sense. Your example is very near to that.

What's the business process you are attempting to model? Why would you need to store data in this way?

Have a look at Designing Historical Tables.

I question if possibly concerns for data presentation are overriding the needs for which you really have to store inside your database.

Do not attempt and make up a model for time unnecessarily. Again this can rely on the company process you are attempting to model and the kind of database solution OLTP/OLAP that you're searching to implement.

For OLTP solutions you'd typically turn to record the specific time (datetime data type for instance) that occasions really occur, instead of modelling all possible time values and looking to relate relevant occasions to occasions. After that you can concentrate on confirming or presentation needs later on.

For OLAP solutions it is extremely common to produce a Date/Calendar Dimension to be able to model time for you to support data statistics and confirming needs.

If utilizing a foreign key you need to go research the actual value within the other table. You may be worried about saving the area however the foreign secret is still a few bytes plus you'd need a catalog around the days table to create searches faster