DataGridView Event to change Column Value

Question

Sir, I am doing a ADO.NET Program and need your help in the following topic.

My Program has a DataGridView named dgvProduct.

It have three fields; Godown and Rack. These are comboBox columns



Godown  Rack
----------  ----------

G1  G1-A

G2  G2-A

G3  G3-A

My function is when I select G1, the Rack column  to be changed  automatically  to G1-A, when G2 then to G2-A......

please provide me the code to function this.