How do you find out the value of a cell in another row?

[Bernard O'Flynn]

Hi
I have the following Datagrid:
Attempts Result
1 Exam1 Button 1 Pass
2 Exam2 Button 2 Fail
3 Exam3 Button 3 -

There is a ExamId that is part of the dataset that is bound to the datagrid.
When the user clicks the button they get taken to a page to take the exam.
How do I
a) determine which button is clicked - the button is generated using a
button column
b) disable the button is the previous exam hasn't been passed yet.
i.e. The button to take Exam 2 is only enabled if the user has passed Exam
1.

Thanks in advance
Bernard