Send field name and DataTable as parameters to Function in C#

Hi,
   When I insert data to some table, I must get the max serial number on the table for now. I create a function to get max serial number on the table.
    How to write the following code to send field name and DataTable  as parameters to Function.

public static int U_MaxSN(string vfield, string vTable)
{
  cmd = "select max(vfield) seriesno from vTable"    <-----here is my problem.
}

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   If I want to get the max serial number on some table .
    vs_seriesno = U_MaxSN(some field name, some table name);

   Thanks.

jeff