select max between two columns in linq

If you're not opposed to ditching the query syntax it's simpler to do:

DateTime max = Products.Max(p=>p.DateSend > p.DateEdit ? p.DateSend : p.DateEdit); 

((from pro in Products.ToList() select pro.DateSend).Union( from pro2 in Products.ToList() select pro.DateEdit )).Max(); 

Same code but with One LinQ

 (From pro in Products.ToList Let max = {pro.DateSend, pro.DateEdit}.Max select max).Max 

If pro items not a valid DateTime, It will crash or return unexpected result.

Other solution(Parsing the Products list items):

 (From pro in Products.ToList Let DSend as DateTime = Convert.ToDateTime(Iif(ValidDateTime(pro.DateSend), pro.DateSend, DateTime.MinValue)) Let DEdit as DateTime = Convert.ToDateTime(Iif(ValidDateTime(pro.DateEdit), pro.DateEdit, DateTime.MinValue)) Let MaxDate as DateTime= {DSend, DEdit}.Max select MaxDate).Max private function ValidDateTime(ByVal Dat as Object) as Boolean if Dat Is Nothing OrElse IsDbNull(Dat) OrElse String.IsNullOrEmpty(Dat) then return false end if return true end function 

You can replace the ValidDateTime with an "Iif".

Other example returning max value of Double items, but in the personalized object(MyObject), items are String type.

 (From Item as MyObject in MyListOfObject Let Frec as Double = Convert.ToDouble(Iif(String.IsNullOrEmpty(Item.Frecuency),0,Item.Frecuency)) Let Pot as Double = Convert.ToDouble(Iif(String.IsNullOrEmpty(Item.Power),0,Item.Power)) Let max as Double= {Frec, Pot}.Max select max).Max 

Recap

1. Declare Column Items separately. Parse It(If you need)
2. Create an Item for store the max value of the row(all columns)
3. Create an Array, put in all declared Items and asign array to the before declared item(Item created in step 2)
4. Append in the end of the array the Max property like this: {Item1, Item2,...}.Max
5. Create Select fr return the Max item
6. Append in the end the linq Max property. (MyLinQ).Max

I hope this code helps to someone. Sorry for my English.