Question

I have a employee draw type application, the tables look like:

Employee (ID, name, selectionCount)

Selections (employeeID, ipAddress)

Now I need an update query that will count the number of selections for each employeeID (with unique IPaddresses), and update the selectionCount column in the table Employee.

Answer 1

Something like this should work:

WITH SelectionCounts(EmployeeId, SelectionCount)
AS
(
    SELECT s.EmployeeId, COUNT(DISTINCT IpAddress) AS SelectionCount
    FROM Selections s
    GROUP BY s.EmployeeId
)
UPDATE Employee
SET SelectionCount = sc.SelectionCount
FROM SelectionCounts sc
WHERE ID = sc.EmployeeId

Did not test it so the syntax may not be completely correct.