How to calculate Rank SQL query

HI, I have the following table which save agent ranking on daily basis on basis of tickets status.

No. **Agent Name** **Incidents** **workorder**  **Rank**     **TimeStamp**
1      cedri开发者_如何学Cc           200          29           1          21 Jan 2011
2      poul             100          10           2          21 Jan 2011
3      dan              200          20           1          21 Jan 2011
4      cedric           100          19           2          22 Jan 2011
5      poul             200          26           1          22 Jan 2011
6      dan              150          20           2          22 Jan 2011

Now i need query which fetch ranking between two dates means if i select date between 21 jan 2011 to 22 jan 2011 then query return me agents average ranking between these two dates of agent not return the agent ranking details on date wise. I need single name of agent with his ranking.

Regards, Iftikhar hashmi

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Try

SELECT [Agent Name], AVG(RANK) FROM MY_TABLE WHERE [TimeStamp] BETWEEN DATE1 AND DATE2
GROUP BY [Agent Name]

(Update)

Thanks to Martin which reminded me I need to cast RANK.

SELECT [Agent Name], AVG(CAST(RANK AS FLOAT)) FROM MY_TABLE WHERE [TimeStamp] BETWEEN DATE1 AND DATE2
GROUP BY [Agent Name]