Question

I am writing a stored procedure in SQL Server Management Studio 2005 to return a list of states and policy counts for two different time periods, month to date and year to date. I have created a couple of views to gather the required data and a stored procedure for use in a Reporting Services report.

Below is my stored procedure:

SELECT DISTINCT
    S.[State],
    COUNT(HP_MTD.PolicyID) AS PolicyCount_MTD,
    COUNT(HP_YTD.PolicyID) AS PolicyCount_YTD
FROM tblStates S
    LEFT OUTER JOIN vwHospitalPolicies HP_MTD ON S.[State] = HP.[State]
        AND HP.CreatedDate BETWEEN DATEADD(MONTH, -1, GETDATE()) AND GETDATE()
    LEFT OUTER JOIN vwHospitalPolicies HP_YTD ON S.[State] = HP.[State]
        AND HP.CreatedDate BETWEEN DATEADD(YEAR, -1, GETDATE()) AND GETDATE()
GROUP BY S.[State]
ORDER BY S.[State] ASC

The problem I am running into is my counts are bloating when a second LEFT OUTER JOIN is added, even the COUNT() that isn’t referencing the second join. I need a left join since not all states will have policies for the given period, but they should still appear on the report.

Any suggestions would be greatly appreciated!

Answer 1

It sounds like you need:

COUNT(DISTINCT HP_MTD.PolicyID) AS PolicyCount_MTD,
COUNT(DISTINCT HP_YTD.PolicyID) AS PolicyCount_YTD

instead of:

COUNT(HP_MTD.PolicyID) AS PolicyCount_MTD,
COUNT(HP_YTD.PolicyID) AS PolicyCount_YTD

Your original query is including the number of matching rows in the second join. Adding a DISTINCT clause inside the COUNT limits it to unique occurrences of the PolicyID.