Vikas,

I searched and discoved this is expected behavior for a few data sources.  Datename does indeed return an integer for data sources that do not have month names.  The conversion actually occurs against the source of the data and in this case there is no call to the DB2 that returns the value of monthname so the numeric value is returned.  You could do a Tableau Extract to resolve the issue or work with a calculated field to convert directly in Tableau. 

Also - I am curious -  the number 10 equal to December.  What is going on there?  Is that a fiscal calendar you are working with? 

Good luck

Patrick 

Hi don't know too much of tableau but:

you can use another calculated field

so

Case Datename('month', Date_field_in_Database)

when 1 then 'January'

When 2 then 'February'

.

.

.

When 12 then 'December'

end

I Used to have the same prob in a report and solved with this

hope be helpful for you too.