Declaration
public static T FirstOrDefault<T>(
    this IQueryable<T> source,
    T default
)Summary
                Returns the first element of a sequence, or a default value if the sequence contains no elements.
Generic type parameters
| T | 
                The type of the elements of source. | 
Parameters
| this IQueryable<T> | source | 
                The collection to return the first element of. | 
| T | default | 
                The default value to return if the sequence contains no elements. | 
Returns
default if 
source is empty; otherwise, the first element in 
source.