What is the fastest way to determine if a row exists using Linq to SQL?

Question

I am not interested in the contents of a row, I just want to know if a row exists. The Name column is a primary key, so there will either be 0 or 1 matching rows. Currently, I am using:

if ((from u in dc.Users where u.Name == name select u).Count() > 0)     // row exists else     // row doesn't exist 

While the above works, it does a lot of unnecessary work by selecting all the contents of the row (if it exists). Does the following create a faster query:

if (dc.Users.Where(u => u.Name == name).Any()) 

...or is there an even faster query?

Answer 1

Of Course

if (dc.Users.Where(u => u.Name == name).Any()) 

this is best and if multiple conditions to check then it is very simple to write as

Say you want to check the user for company then

if (dc.Users.Where(u => u.ID== Id && u.Company==company).Any()) 

Answer 2

The Count() approach may do extra work, as (in TSQL) EXISTS or TOP 1 are often much quicker; the db can optimise "is there at least one row". Personally, I would use the any/predicate overload:

if (dc.Users.Any(u => u.Name == name)) {...} 

Of course, you can compare what each one does by watching the TSQL:

dc.Log = Console.Out;