Difference between Select & Where in Linq

While implementing a condition in my project I got confused because of the use of Where & Select in Linq .

The scenario was

int _finalcount = ComponentFiles.Where(x => x.FileLocationTypeID.HasValue && x.FileLocationTypeID.Value == 4).Count();

 

int _finalcount = ComponentFiles.Select(x => x.FileLocationTypeID.HasValue && x.FileLocationTypeID.Value == 4).Count();

 My requirement was to find the count of File types with is satisfy the condition. Initially I have tried with select & it is always return count as ‘1’ instead of ‘0’. After a long analyses I found my foolish mistake.

I searched the difference between the two operations find the exact result.

Select is a projection, so what you get is the expression x=> x. FileLocationTypeID.Value == 4 evaluated for each element in ComponentFiles on the server. i.e. lots of true/false values (the same number as your original list). If you look the select will return something like IEnumerable<bool> (because the type of x.FileLocationTypeID.Value == 4 is a bool).

Where filters the results, returning an enumerable of the original type (no projection).

Simply say Where() is a filter.Select() selects a different piece of data