如何在数据表中检查For循环内的条件时如何丢弃Null值?

In my Project I select the User ID based Upon some Condition from DB and save it in Datatable and checking it with the ID entered by the User based Upon Condition only 5 rows will be fetched but in the loop and in IF condition it is Checking with the 6th row which is null so it throws the Exception "There is no row at Position 6" My Code is In my Project I select the User ID based Upon s