You can try this for building the update query:
SqlCommandBuilder build = new SqlCommandBuilder(adapter);
and on update record button click event write the below line:
adapter.Update(dt);
here adapter is a object of SqlDataAdapter and dt is object of DataTable. And make sure your table contains Primary key.
refer this to learn more:
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommandbuilder.aspx?ppud=4[
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hope it helps :)
for further queries comment here!!