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sql to linq in c# code

cn.Open();
            SqlCommand cmsql;
            SqlDataReader drsql;


            string sql = "select max(patientid)as patientid from patient";



            cmsql = new SqlCommand(sql, cn);

            drsql = cmsql.ExecuteReader();
            if (drsql.Read())
            {
         
                    int pid = Convert.ToInt16(drsql["patientid"].ToString()) + 1;
                    txtpatientid.Text = pid.ToString();
                

            }


            else
            {

                txtpatientid.Text = "1";
            }
            cn.Close();
            cmsql.Dispose();
            drsql.Close();

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this is my sql code how i make it in linq

my table name is== patient

Habib Pourfard

using (MyDataContext dc = new MyDataContext())
{
    int pid = dc.patients.Max(t => t.patientid);
}

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ASKER CERTIFIED SOLUTION

Fernando Soto

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loveuajay

ASKER

i get this error

Error 1 The type or namespace name 'DataContextType' could not be found (are you missing a using directive or an assembly reference?) D:\ajay\jolly tech project\jollytech p1\jollytech p1\patient.cs 79 26 jollytech p1

Fernando Soto

Hi loveuajay;

When working with Linq to SQL the first thing you need to do is create your data context and in Linq to SQL it is creating a EDMX which is Object Relational/Model, This model defines the tables in the database and the relationships between them. I would suggest reading the following web link which describe what LinQ to SQL is and how to create the OR/M, EDMX file and querying the database.

Using Linq to SQL Part 1

Once you have created the EDMX file which maps the database to the classes in your code that is what you will use for the variable DataContextType in the code snippet I posted.

loveuajay

ASKER

thanks i get it

Fernando Soto

Not a problem, glad to help.