mcommand is DataAdapter 

DataAdapter object is like a bridge that links the database 
and a Connection object with the ADO.NET-managed DataSet 
object through its SELECT and action query Commands. It 
specifies what data to move into and out of the DataSet. 
Often, this takes the form of references to SQL statements 
or stored procedures that are invoked to read or write to a 
database.
The DataAdapter provides four properties that allow us to 
control how updates are made to the server:
* SelectCommand
* UpdateCommand
* InsertCommand
* DeleteCommand