Feeds2Read: RSS FEED .: enterprise, etc Blogs :. DataReaders are a nice quick way to get forward-only, read-only access to data from a data source.  If you are building a data access layer, it would be nice to be able to execute a query against the data source, produce a DataReader object and then pass that object back out of the data access layer to some calling class.  Thing is, when your reader is produced, the data is only readable from it while the database connection is live.  If that connection is created inside the data access layer, as soon as it goes out of scope, the reader is useless.  For example, see the code below. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p> </o:p> public IDataReader ExecuteReader(string as_connstr, string as_sql)<o:p></o:p> {<o:p></o:p>     MySqlConnection lobj_cn = new MySqlConnection(as_connstr);<o:p></o:p>     MySqlCommand lobj_cmd = new MySqlCommand(as_sql, lobj_cn);<o:p></o:p>     MySqlDataReader lobj_reader;<o:p></o:p> <o:p> </o:p>     <o:p></o:p>     <o:p></o:p>         lobj_cn.Open();<o:p></o:p>         lobj_reader = <o:p></o:p> lobj_cmd.ExecuteReader();<o:p></o:p>     <o:p></o:p>     <o:p></o:p>     <o:p></o:p>         <o:p></o:p>     <o:p></o:p>         return lobj_reader;<o:p></o:p> }<o:p></o:p> <o:p> </o:p> As soon as we return the reader, this method ends and connection we created goes out of scope.  Without a connection, the reader is of no use to us.  What we need, is a way to keep the connection alive outside the scope of the method.  Sure, we could create the connection outside this method call and pass it in instead of the connection string.  But, then we are putting the responsibility of managing the connection lifetime outside the data access layer.<o:p></o:p> <o:p> </o:p> There is a better way, though.  The reader has a propery that basically tells it to take over the management of the connection for itself.  Here is our modified method.<o:p></o:p> <o:p> </o:p> public IDataReader ExecuteReader(string as_connstr, string as_sql)<o:p></o:p> {<o:p></o:p>     MySqlConnection lobj_cn = new MySqlConnection(as_connstr);<o:p></o:p>     MySqlCommand lobj_cmd = new MySqlCommand(as_sql, lobj_cn);<o:p></o:p>     MySqlDataReader lobj_reader;<o:p></o:p> <o:p> </o:p>     <o:p></o:p>     <o:p></o:p>         lobj_cn.Open();<o:p></o:p>         lobj_reader = <o:p></o:p> lobj_cmd.ExecuteReader(CommandBehavior.CloseConnection);<o:p></o:p>     <o:p></o:p>     <o:p></o:p>     <o:p></o:p>         <o:p></o:p>     <o:p></o:p>         return lobj_reader;<o:p></o:p> } <o:p> </o:p> Notice the addition in red.  By calling the method in this way, we are basically telling the reader to do the right thing with the connection.  When the reader is used to read to the end, the connection is closed.if the reader is destroyed, the connection is also closed., RSS Feeds Aggregator and RSS Directory

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