Question

I wrote a procedure which actually searches a record.
when i execute it, it gives an error which says:

Conversion failed when converting date and/or time from character string.

Statement:

((CONVERT(varchar, DATEPART(YYYY, Tbl_Contract.ContractDate), 101)) = @Year or @Year = '')

Answer 1

Since ContractDate is a Varchar you can either parse directly with

SubString(ContractDate, x, 4) = @YearString 

or you can encapsulate the condition

Case when IsDate(ContractDate) = 1 
      then ((CONVERT(varchar, DATEPART(YYYY, @a), 101))) 
      else NULL 
end