finding date in sql

i need a query to find the date based on year, month, day of the week and weekday number. Say for example, if the question is to find the date of 2nd Sunday of January 2010, the answer should be '2010-01-10'.

Inputs are

Yr   | Mon | Dy  | Dyno
---------------------开发者_StackOverflow社区--
2010 | Jan | Sun | 2
2005 | Jan | Mon | 3
1995 | Feb | Sun | 1
2000 | Feb | Wed | 4
1982 | Mar | Tue | 2
2010 | Mar | Tue | 8

Dyno states dayno

The easiest answer to many date-related questions in SQL is to create a calendar table. In your case, if you create a table with the columns you've already shown, and an extra one with the DATETIME value that you want (call it BaseDate), you can get the value you need with a simple query:

select BaseDate
from dbo.Calendar
where Yr = 2010 and Mon = 'Jan' and Dy = 'Sunday' and Dyno = 2

Of course, your calendar table can have 10, 20 or more columns, depending on what values you find useful for your queries.