Solved: Table Design / SQL Design Advice

[Bob Phillips]

I was going to ask you about that HAVING. Having is used to filter aggregate items, not row items, so doesn't seem necessary here. I think

PARAMETERS lEmpID Long, dtFrom DateTime, dtTo DateTime; 
SELECT TP.empID, SUM(DateDiff("n",[dtTimeIn],[dtTimeOut])/60) AS Hours 
FROM tblTimePairs As TP 
WHERE (TP.dtWork BETWEEN [dtFrom] AND [dtTo]) AND (TP.empID=[lEmpID])
GROUP BY TP.empID ;

should be sufficient.

BTW, it is convention to use upper-case for keywords.