Use Microsoft.Data.DataConnectionDialog in your projects to retrieve connection string

This is the use of the Visual Studio connection dialog in your own projects, for instance tool kits to inspect databases. Steps are:

1. NuGet
2. Search and add Data Connection (Windows Forms)
3. Add code, sample is in VB, but C# is similar

Imports Microsoft.Data.ConnectionUI

    Private Sub GetDataConnection()

        Dim dcd As New DataConnectionDialog
        DataSource.AddStandardDataSources(dcd)
        dcd.SelectedDataSource = DataSource.SqlDataSource

        If DataConnectionDialog.Show(dcd) = Windows.Forms.DialogResult.OK Then
            Select Case dcd.SelectedDataProvider.Name
                Case DataProvider.SqlDataProvider.Name
                    Dim cn As New SqlClient.SqlConnection(dcd.ConnectionString)
                    DataSourceToolStripTextBox.Text = cn.DataSource
                    DatabaseDefaultToolStripTextBox.Text = cn.Database
                    'MessageBox.Show(String.Concat("Found SQL: ", cn.ConnectionString))

                Case Else
                    MessageBox.Show(dcd.ConnectionString)
            End Select
        End If

    End Sub

See also
http://wildermuth.com/2007/1/29/Using_the_Visual_Studio_Connection_String_Dialog