Insert data into database using LINQ

Question

I wrote a very simple method. It saves data from class DayWeather to the database. Method checks if line with that day exist in table and update her or create a new line.

I am doing it by adding new class for LINQ and move table from Server Inspector to the constructor. It generate new class WeatherTBL.

Method itself looks like this:

public static void SaveDayWeather(DayWeather day)
    {
        using (DataClassesDataContext db = new DataClassesDataContext())
        {
            var existingDay =
              (from d in db.WeatherTBL
               where d.DateTime.ToString() == day.Date.ToString()
               select d).SingleOrDefault<WeatherTBL>();
            if (existingDay != null)
            {
                existingDay.Temp = day.Temp;
                existingDay.WindSpeed = day.WindSpeed;
                existingDay.Pressure = day.Pressure;
                existingDay.Humidity = day.Humidity;
                existingDay.Cloudiness = day.Cloudiness;
                existingDay.TypeRecip = day.TypeRecip;
                db.SubmitChanges();
            }
            else
            {
                WeatherTBL newDay = new WeatherTBL();
                newDay.DateTime = day.Date;
                newDay.Temp = day.Temp;
                newDay.WindSpeed = day.WindSpeed;
                newDay.Pressure = day.Pressure;
                newDay.Humidity = day.Humidity;
                newDay.Cloudiness = day.Cloudiness;
                newDay.TypeRecip = day.TypeRecip;
                db.WeatherTBL.InsertOnSubmit(newDay);
                db.SubmitChanges();
            }
        }
    }

When I tried to call him from UnitTest project:

  [TestMethod]
    public void TestDataAccess()
    {
        DayWeather day = new DayWeather(DateTime.Now);
        DataAccessClass.SaveDayWeather(day);
    }

It write, that test has passed successfully. But if look into table, it has`t chanched. No error messages shows. Does anyone know whats the problem?

P.S. Sorry for my bad English.

UDP Problem was in that: "...db maybe copied to the debug or release folder at every build, overwriting your modified one". Thanks @Silvermind

I am not sure why it is not storing the data. However your unit test is just calling the method but not using assert to validate the result. — Amit Rai Sharma
– Amit Rai Sharma, Commented May 5, 2013 at 19:21
@ARS, He don`t have result for validate. Method returns void. And I check the result into table... — Advers191
– Advers191, Commented May 5, 2013 at 19:30
I see. You can still write a method to retrieve the data and perform an assert. Anyway that is a different topic of discussion. Can you check the connection string to see if the data is inserted into the right db. — Amit Rai Sharma
– Amit Rai Sharma, Commented May 5, 2013 at 19:39
Besides the point offered by @ARS about the connection string, are your entity properties mapped? — Silvermind
– Silvermind, Commented May 5, 2013 at 19:50
If you did this 2.Drag the Customers node from Server Explorer/Database Explorer onto the O/R Designer surface. than they are automatically mapped, but if you change anything int the database after that you should redo it, or change Source in the dbml properties-page for that Entity, Also: your db maybe copied to the debug or release folder at every build, overwriting your modified one. Are you also looking at the right file (Check your Release/Debug folder)? — Silvermind
– Silvermind, Commented May 5, 2013 at 20:10

Hille · Accepted Answer · 2023-01-17 14:12:33Z

9

I wrote simple method to save employee details into Database.

private void AddNewEmployee()
{
    using (DataContext objDataContext = new DataContext())
    {                
        Employee objEmp = new Employee();
        // fields to be insert
        objEmp.EmployeeName = "John";
        objEmp.EmployeeAge = 21;
        objEmp.EmployeeDesc = "Designer";
        objEmp.EmployeeAddress = "Northampton";                
        objDataContext.Employees.InsertOnSubmit(objEmp);
        // executes the commands to implement the changes to the database
        objDataContext.SubmitChanges();
    }
}

edited Jan 17, 2023 at 14:12

Hille

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answered Jun 8, 2015 at 14:05

Arun Kumar

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Comments

Pranab Kumar De · Accepted Answer · 2016-01-25 08:50:58Z

0

Please try with lambda expression. In your code, var existingDay is of type IQueryable In order to insert or update, you need a variable var existingDay of WeatherTBL type. Hence try using below..

 var existingDay =
 db.WeatherTBL.SingleOrDefault(d => d.DateTime.Equals(day.Date.ToString()));

 if(existingDay != null)
  {
   //so on...
  }

Hope it should work..

answered Jan 25, 2016 at 8:50

Pranab Kumar De

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Comments

Ahsan · Accepted Answer · 2019-08-09 12:41:58Z

0

Linq to SQL

        Detail tc = new Detail();


        tc.Name = txtName.Text;
        tc.Contact = "92"+txtMobile.Text;
        tc.Segment = txtSegment.Text;
        var datetime = DateTime.Now;
        tc.Datetime = datetime;
        tc.RaisedBy = Global.Username;
        dc.Details.InsertOnSubmit(tc);

        try
        {


            dc.SubmitChanges();
            MessageBox.Show("Record inserted successfully!");
            txtName.Text = "";
            txtSegment.Text = "";
            txtMobile.Text = "";

        }


        catch (Exception ex)
        {
            MessageBox.Show("Record inserted Failed!");

        }

answered Aug 9, 2019 at 12:41

Ahsan

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