Cómo agregar el valor predeterminado a Combobox en WPF

<ComboBox Name="cbxType" HorizontalAlignment="Left" Margin="116,41,0,0" VerticalAlignment="Top" Width="192">
    <ComboBoxItem Name="create" IsSelected="True">create database</ComboBoxItem>
    <ComboBoxItem Name="update">update database</ComboBoxItem>
</ComboBox>
Obnoxious Oystercatcher