Nested Gridview

Hi, I am using datatable to get the datas read from the excel sheet, and stored in Parent and child gridview using a datatable,
S.no
1  Name
   a 1 2 3 4
   b 4 5 6 7
   c 1 2 8 5
   d 8 9 8 4 
2 Department
   a 1 2 3 4
   b 4 5 6 7
Name,Department-Parent gridview When i click the Name or Department child grid opens
I should get the four rows in the child gridview when i click Name filed and if i click Department i should 2 rows.
There will be empty spaces between s.no. How to get the respective rows in a datatable
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