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How do I get the max ID with Linq to Entity?

Posted by: admin November 29, 2017 Leave a comment

Questions:

I have a table User which has an identity column UserID, now what is the correct Linq to Entity line of code that would return me the max UserID?

I’ve tried:

using (MyDBEntities db = new MyDBEntities())
{
    var User = db.Users.Last();
    // or
    var User = db.Users.Max();

    return user.UserID;
}

but Last and Max don’t seem to be supported.

Any ideas?

Answers:

Try with

db.Users.OrderByDescending(u => u.UserId).FirstOrDefault()

Questions:
Answers:

try this

int intIdt = db.Users.Max(u => u.UserId);

Update:

If no record then generate exception using above code try this

int? intIdt = db.Users.Max(u => (int?)u.UserId);

Questions:
Answers:

NisaPrieto

Users user = bd.Users.Where(u=> u.UserAge > 21).Max(u => u.UserID); 

will not work because MAX returns the same type of variable that the field is so in this case is an INT not an User object.

Questions:
Answers:
var max = db.Users.DefaultIfEmpty().Max(r => r == null ? 0 : r.ModelID);

when there are no records in db it would return 0 with no exception.

Questions:
Answers:

In case if you are using the async and await feature, it would be as follows:

User currentUser = await db.Users.OrderByDescending(u => u.UserId).FirstOrDefaultAsync();

Questions:
Answers:

The best way to get the id of the entity you added is like this:

public int InsertEntity(Entity factor)
{
    Db.Entities.Add(factor);
    Db.SaveChanges();
    var id = factor.id;
    return id;
}