Linq query return true or false

Question

I have a query where it should return TRUE or FALSE.

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID &&         


        

Answer 1

try this,

 var query = (from c in db.Emp
        from d in db.EmpDetails 
        where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D"
         select c 
         ).Any(); 

  this.result = query; //no need to convert to boolean its already bool value

Answer 2

var query = from c in db.Emp
            from d in db.EmpDetails 
            select new { c.ID == y.ID &&  
                         c.FirstName == "A" && 
                         c.LastName == "D" };

Answer 3

If you really want to have a "true" or "false" String Response:

    public string result
    {
        get
        {
            return db.Emp.SelectMany(c => db.EmpDetails, (c, d) => new {c, d})
                         .Where(@t => c.ID == y.ID && c.FirstName == "A" && c.LastName == "D")
                         .Select(@t => c)).Any().ToString();
        }
    }

But I would suggest to make the property "result" a bool and remove the ToString(). Once you have a bool you can always do a ToString() on it

Answer 4

If I understand you correctly you want to get true if one of the results of the query matches all conditions. In that case try something like this:

var found =
    (from c in db.Emp
    from d in db.EmpDetails
    where c.ID == y.ID && c.FirstName == "A" && c.LastName == "D"
    select c).Any();

this.result = found.ToString();

Answer 5

You can use .Any() or .Count(). Any() is performing better. (Check this SO question to see why)

.Any()

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions
this.result = query.Any().ToString()

.Count()

var query = from c in db.Emp
            from d in db.EmpDetails 
            where c.ID == d.ID && c.FirstName == "A" && c.LastName == "D" 
          // It should return TRUE when this above statement matches all these conditions
this.result = (query.Count() > 0).ToString()