In this article I will explain with an example, how to use Output Parameter in SQL Server Stored Procedure with Dapper library in Windows Forms (WinForms) Application using C# and VB.Net.
 
 

Installing Dapper package using Nuget

In order to install Dapper library using Nuget, please refer my article Install Dapper from Nuget in Visual Studio.
 
 

Database

I have made use of the following table Customers with the schema as follows.
Using Output Parameter in Stored Procedure with Dapper using C# and VB.Net
 
Note: You can download the database table SQL by clicking the download link below.
          Download SQL file
 
 

Stored Procedure

The following Stored Procedure will be used to Insert data into the SQL Server database table.
This Stored Procedure accepts following parameters which are used to insert the records:
Name – This is an INPUT Parameter to pass the Name of the Customer.
Country – This is an INPUT Parameter to pass the Country of the Customer.
CustomerId – This is an OUTPUT Parameter to get the last inserted CustomerId.
Note: Output Parameter is identified by the keyword OUTPUT.
 
CREATE PROCEDURE [Customers_InsertCustomer_Output]
      @Name VARCHAR(100),
      @Country VARCHAR(50),
      @CustomerId INT OUTPUT
AS
BEGIN
      INSERT INTO [Customers]
                  ([Name]
                  ,[Country])
      VALUES      (@Name
                  ,@Country)
 
      SELECT @CustomerId = SCOPE_IDENTITY()
END
 
 

Form Design

The following Form consists of:
Label – For labeling controls.
TextBox – For capturing Name to be inserted.
ComboBox – For capturing Country Name to be inserted.
Button – For inserting records.
The Button has been assigned with a Click event handler.
Using Output Parameter in Stored Procedure with Dapper using C# and VB.Net
 
 

Namespaces

You will need to import the following namespaces.
C#
using Dapper;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
 
VB.Net
Imports Dapper
Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
 
 

Inserting with Stored Procedure using Dapper in Windows Forms

Inside the Form Load event handler, the ComboBox items are added.
When Insert button is clicked, first the connection is read from App.Config file.
Note: For more details on how to read connection string from App.Config file, please refer my article .Net 4.5: Read (Get) Connection String from App.Config file using C# and VB.Net.
 
An object of DynamicParameters is created and CustomerId is added as parameter with its Data Type specified and its Direction is set to Output since by default the Direction of all parameter are Input.
Then, the Name and Country values are also added as parameter.
After that, the Execute method of Dapper library is used to insert record to the Customers Table.
Note: For more details on Execute method, please refer my article Understanding Dapper Execute in C# and VB.Net.
 
The CustomerId of the inserted record i.e. the output parameter value is fetched using Get method of DynamicParameters class.
Finally, the TextBox and ComboBox values are set to empty and CustomerId of the inserted record is displayed in MessageBox.
C#
private void Form1_Load(object sender, EventArgs e)
{
    cbCountries.Items.Add("United States");
    cbCountries.Items.Add("India");
    cbCountries.Items.Add("France");
    cbCountries.Items.Add("Russia");
}
 
private void OnInsert(object sender, EventArgs e)
{
    int customerId;
    string spName = "Customers_InsertCustomer_Output";
    string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        DynamicParameters dynamicParameters = new DynamicParameters();
        // Adding Input parameters.
        dynamicParameters.Add("@Name", txtName.Text);
        dynamicParameters.Add("@Country", cbCountries.SelectedItem.ToString());
        // Adding Output parameter.
        dynamicParameters.Add("@CustomerId", dbType: DbType.Int32, direction: ParameterDirection.Output);
        con.Execute(spName, dynamicParameters, commandType: CommandType.StoredProcedure);
        customerId = dynamicParameters.Get<int>("@CustomerId");
    }
 
    txtName.Text = string.Empty;
    cbCountries.Text = string.Empty;
    MessageBox.Show("Inserted Customer ID: " + customerId);
}
 
VB.Net
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
    cbCountries.Items.Add("United States")
    cbCountries.Items.Add("India")
    cbCountries.Items.Add("France")
    cbCountries.Items.Add("Russia")
End Sub
 
Private Sub OnInsert(sender As Object, e As EventArgs) Handles btnInsert.Click
    Dim customerId As Integer
    Dim spName As String = "Customers_InsertCustomer_Output"
    Dim constr As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As SqlConnection = New SqlConnection(constr)
        Dim dynamicParameters As DynamicParameters = New DynamicParameters()
        ' Adding Input parameters.
        dynamicParameters.Add("@Name", txtName.Text)
        dynamicParameters.Add("@Country", cbCountries.SelectedItem.ToString())
        ' Adding Output parameter.
        dynamicParameters.Add("@CustomerId", dbType:=DbType.Int32, direction:=ParameterDirection.Output)
        con.Execute(spName, dynamicParameters, commandType:=CommandType.StoredProcedure)
        customerId = dynamicParameters.Get(Of Integer)("@CustomerId")
    End Using
 
    txtName.Text = String.Empty
    cbCountries.Text = String.Empty
    MessageBox.Show("Inserted Customer ID: " & customerId)
End Sub
 
 

Screenshots

The Form

Using Output Parameter in Stored Procedure with Dapper using C# and VB.Net
 

Record after Insert in database

Using Output Parameter in Stored Procedure with Dapper using C# and VB.Net
 
 

Downloads

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