I have a customer service database where employees record transactions with customers and each entry is date stamped.  I also have a table where users record their hours worked so I can keep track of productivity. Users have to log in using their ID and password.  Here is what I want to do:
When users log in every day, I want to be able to query whether or not they have any data entered in the customer service table but no entries for that corresponding date in the hours worked table.  In other words, If they haven't entered any hours worked for a particular day that they entered data, I want to create a pop-up that will remind them to enter their missed hours for that particular date.  I'd like to do this where as soon as they log in, the query runs and they get this popup.  Any suggestions?

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Reply from Alex Hedley:

Create a parameter Query that has a where condition of ID and a BETWEEN date and pass in Now() with +/-1,
You could use a DCount for this query and if 0 then show message.