.net - How to convert Binary to Byte and write as a file in c# -

i trying read binary database , write file in local disk using c#.

using below code... there problem in line : byte[] fileasbyte = byte.parse(row["blob"]);

public static void readblob() {      int icount = 0;     string filename;     sqlconnection mycon = new sqlconnection(con);     mycon.open();     string querystring = "select * " + tblname;     sqldataadapter adapter = new sqldataadapter(querystring, mycon);      datatable dtblob = new datatable();     adapter.fill(dtblob);       foreach (datarow row in dtblob.rows)     {         byte[] fileasbyte = byte.parse(row["blob"]);         filename = filepath + tblname + row["blobid"].tostring() + filetype;          writeblob(fileasbyte, filename);     }      mycon.close(); }  public static void writeblob(byte[] buff, string filename) {     try     {         filestream fs = new filestream(filename, filemode.create, fileaccess.readwrite);         binarywriter bw = new binarywriter(fs);         bw.write(buff);         bw.close();      }     catch (exception ex)     {         console.writeline(ex.message);     }  } 

byte.parse try parse single byte. have tried casting?

byte[] fileasbyte = (byte[]) row["blob"]; 

if fails, should @ least show type actually in datarow. it's type reasonably convertible byte[].