Hidden Field to filter values

Question

Hi experts,
I would like to bind one of my dropdown list to my database using Hidden Field to filter the values, but faced difficulties in doing so.
I have this field for Week Type(DDLWeek) and the value in the dropdown list is different from my database value.
Thus i would like to ask, how can I bind it so that the value I retrieve out is the database value instead of the dropdown list value?
For example, the value for my ddlWeek is "Odd", however my database value is "O".
Here is the codes which i am using:
 

 DataTable resultTable = 
dbAdapter.selectWeek((string)Session["userName"], 

DDLWeek.SelectedItem.Value, DDLYear.SelectedItem.Value, 

DDLSemester.SelectedItem.Value);

 
Thank you for your kind assistance.
Best Regards.