Drop down according to rows in table control

Hi Experts,

I have a table control on screen which has 2 columns out of which 1 column is dropdown.

Now,what i want is "depending on value in (row 1 column 1),the values in drop down box (row 1 column 2) should change.Similarly,depending on alues in (row 2 column1),the values in (row 2 column 2) should change"...

How can we do this??

Kindly reply...