Hi,
I’m using VS2005 and I’m trying to link the C# windows form to MSSQL. I used BindingNavigator Control to read the data. After that I add sqlcommand and sqldataadapter to send the data to the database. My code is this

  sqlDataAdapter1.InsertCommand.CommandText =
         "INSERT INTO STUDENT (" +
         "S_ID, S_NAME, S_ADDRESS, S_PHONE" +
         ") VALUES ('" +
         S_IDComboBox.Text + "', '" +
         S_NAMETextBox.Text + "', '" +
         S_ADDRESSTextBox.Text + "', '" +
         S_PHONETextBox.Text + "')";

sqlDataAdapter1.InsertCommand.ExecuteNonQuery();

It gave me this error
“NulleferenceException was Unhandled”and “ Object refrence not set to an instance of an object” so I add this line

    sqlCommand1 = ("INSERT INTO STUDENT (S_ID,S_NAME,S_ADDRESS,S_PHONE) VALUES (@S_ID,@S_NAME,@S_ADDRESS,@S_PHONE)" ,sqlConnection1);

    Then it gave me some stupid error. By the way it didn’t make a new object of SqlCommand although I tried ….

So can u help me to solve my problem ? Thank you

Check you entered valid values for all fields. SQL try to save NULL for the field which Allow Null property set to false.