How to set Combo box value in WPF using MVVM architecture

Question

I created a POC in WPF MVVM architecture.In which I used combo box control you can see in the code below.

 

<ComboBox Name="DeptCombo" Grid.Row="4" Grid.Column="1" ItemsSource="{Binding DepartmentList,Mode=TwoWay}" SelectedItem="{Binding Path=CurrentDepartment,Mode=TwoWay}" DisplayMemberPath="DepartmentName">

</ComboBox>

 

Everything is fine, I binded that combo , saved that combo value in the database, But the only problem I was facing is, I am not able to set the saved database value in that combo.I don't get any solution regarding that.Please help me.