if a date is between 2 dates

Hello. 

I have the following problem:

2 tables:

- "Dates": a date table with 3 columns: Date (calendar dates); inferiordate (calendar date - 2 days + 16h); superiordate (calendar date - 1 day + 15h59);

correcteddate: (

if weekday of superiordate = saturday; adds 3 days to superiordate; 

if weekday of superiordate = sunday; adds 2 days to superiordate; 

if weekday of superiordate = monday; adds 1 days to superiordate; 

if weekday of superiordate = friday; adds 3 days to superiordate; 

else; adds 1 days to superiordate; 

This means that the correctedate will have duplicate dates. 

Then, I have other table with production data and with "End of assignment" timestamp.

I want to do the following: 

If [end of assignment] is between inferiordate and superiordate, assume correcteddate. 

The problem is that I can't create relationships between the tables because I have repeteated dates. 

Any help?

Thanks.