If you do not call ToList()
and your final mapping to the DTO type, you can add Where
clauses as you go, and build the results at the end:
var query = from u in DataContext.Users
where u.Division == strUserDiv
&& u.Age > 18
&& u.Height > strHeightinFeet
select u;
if (useAge)
query = query.Where(u => u.Age > age);
if (useHeight)
query = query.Where(u => u.Height > strHeightinFeet);
// Build the results at the end
var results = query.Select(u => new DTO_UserMaster
{
Prop1 = u.Name,
}).ToList();
This will still only result in a single call to the database, which will be effectively just as efficient as writing the query in one pass.