Optional condition not working linq

Question

I having some problem in Optional condition in Lambda express like

var shouldCheckDate = !string.IsNullOrEmpty(fromDate);
var result = (from r in db.Notify
              where r.ApplicationId == applicationId
              && (shouldCheckDate || r.CreatedDate.Date > date)
              select r
              ).Count;

problem is here it always excuting both condition either shouldCheckDate true are false. I am doing any thing wrong?

Answer 1

这是由于以下事实：与C＃相比，LINQ被转换为SQL，并且SQL执行条件的所有部分，无论它们中的任何一个是否都已返回true。

Answer 2

You could compose the IQueryable by adding the where clauses only when needed:

var query = db.Notify;
query = query.Where(r => r.ApplicationId == applicationId);
if (shouldCheckDate) {
    query = query.Where(r => r.CreatedDate.Date > date);
}
var result = query.Count();

Answer 3

You have OR statement here,

(shouldCheckDate || r.CreatedDate.Date > date)

so even one of these conditions which is true is enough for whole statement to be true.

Maybe r.CreatedDate.Date is always > date ?