title: How to cast a string to nvarchar?
body: <p>I have a text box and I want to save the output result to <strong>Unicode</strong>  (<code>nvarchar</code> in SQL Server), for the save operation I used Entity Framework, my code works fine, my problem is just to convert the text box result to Unicode, because when i saved the result it saved as "?" in Sql Server.
  NB:<strong>i use Arabic letters.</strong>, this is my code , and column definition:
  <strong>Code</strong> :</p>
  
  <pre><code>//Button add new car into database
      private void BtnAddNewCar_Click(object sender, EventArgs e)
      {
          v.brand = TxBoxBrand.Text;
          v.car_number = TxBoxCarNumber.Text;//Text Box that i want to convert to Unicode (Arabic letters)
          v.color = CmBoxColorPicker.Text;
          v.model = TxBoxModel.Text;
          v.picture = ImageToByteArray(filename);
          v.cin_driver= CmBoxCarOwner.Text;
          context.Vehicles.Add(v);
          context.SaveChanges();
          NotifyWelcome.ShowBalloonTip(1000, "The vehicle " + TxBoxBrand.Text + " was successfully added", " Have a ice drive", ToolTipIcon.Info);
          CarClear();
          VLoad.Enabled = true;
          CmVLoad.Enabled = false;
          MyMessageBox.ShowBox("The vehicle " + TxBoxBrand.Text + " as successfully added", "Notify");
      }
  </code></pre>
  
  <p><strong>Column definition</strong> :</p>
  
  <pre><code>// TxBoxCarNumber
          // 
          this.TxBoxCarNumber.Font = new System.Drawing.Font("Ubuntu", 9F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
          this.TxBoxCarNumber.Location = new System.Drawing.Point(272, 30);
          this.TxBoxCarNumber.Name = "TxBoxCarNumber";
          this.TxBoxCarNumber.Size = new System.Drawing.Size(142, 21);
          this.TxBoxCarNumber.TabIndex = 0;
          this.TxBoxCarNumber.TabStop = false;
  </code></pre>