CODEWITHSUNDEEP
c#linqvisual-studio-2008
Omneya
Omneya

Reputation: 557

get last record of a table in database?

i am developing a project and after the user insert the data of the customer he suppose to print the ID and the name of the Customer , this is the code of the ID 

int getPatnID()
    {
        int ID = (from i in Db.Patients
                  select i.patn_ID).Max();
        return ID;
    }

i have write the code to get the name but i cant finish it

string getPatnName()
    {
        string name = (from n in Db.Patients
                       select n.patn_name).

        return name;
    }

How should i write to complete it ??

Upvotes: 1

Views: 15983

Answers (6)

Thebigcheeze
Thebigcheeze

Reputation: 3498

This should always get the last inserted record at time of execution (assuming patn_id is auto-incrementing)

string GetPatnName() 
{
    string name = (from n in Db.Patients 
                   orderby n.patn_ID descending 
                   select n.patn_name).FirstOrDefault();
    return name;
}

Upvotes: 4

Johnv2020
Johnv2020

Reputation: 2146

Why not just create a patient class an return an instance as shown below

public class Patient
{
    public int PatientID { get; set; }
    public string Name { get; set; }
}


static Patient getDetails()
    {
        using (DataClasses1DataContext db = new DataClasses1DataContext())
        {
            var c = (from x in db.Patients.OrderByDescending(u => u.PatientID)
                     select new Patient()
                     {
                         PatientID = x.PatientID,
                         Name = x.Name
                     }).FirstOrDefault();
            return c;
        }

Upvotes: 0

jeroenh
jeroenh

Reputation: 26792

Getting the id the way you do is wrong. Not sure what you're using, but both linq-2-sql and entity framework fill in the entity Id when saving changes:

    Patient patient = new Patient();
    Console.WriteLine(patient.Id); // will NOT be filled in
    Db.Patients.Add(patient);
    Db.SubmitChanges(); // SaveChanges in EF
    Console.WriteLine(patient.Id); // will be filled in

Upvotes: 0

user19302
user19302

Reputation: 

string getPatnName() {
    string name = Db.Patients.Last(p => p.patn_ID).patn_name;
    return name;
}

I suggest you spend some more time studying LINQ - it is a very rich and powerful library: http://msdn.microsoft.com/en-us/library/bb397926.aspx

Upvotes: 1

nycdan
nycdan

Reputation: 2849

If you are trying to get the name of the last patient you just entered, and you have the ID from the first query, you just need a where clause in your LINQ.

string name = (from n in Db.Patients
       where n.patn_ID == ID
       select n.patn_name);

Upvotes: 1

manji
manji

Reputation: 47968

Change getPatnName to take an id:

string getPatnName(int id)
{
    string name = (from n in Db.Patients
                   where n.patn_ID == id
                   select n.patn_name).SingleOrDefault();

    return name;
}

and give it the result of getPatnID()

Upvotes: 1

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