在.net中应用事务

Code
public bool ModifyDynamicAccount(DynamicAccountInfo daInfo, string DeviceId)
 2     {
 3         conn = Myconn.SqlConnection;
 4         string sqlstr1 = "update DynamicAccountFlow set EDate='" + daInfo.SDate + "' from DynamicAccount a inner Join DynamicAccountFlow b on a.Guid=b.Guid where b.DeviceID='" + DeviceId + "'";
 5         string sqlstr2 = "update DynamicAccount set DeviceID='" + daInfo.DeviceID + "',UseMonth='" + daInfo.UseMonth + "',AccuAmort='" + daInfo.AccuAmort + "',NetWorth='" + daInfo.NetWorth + "',State='" + daInfo.State + "',DeptID='" + daInfo.DeptID + "',RepairPlace='" + daInfo.RepairPlace + "',FaceID='" + daInfo.FaceID + "',DeviceSource='" + daInfo.DeviceSource + "',SDate='" + daInfo.SDate + "',EDate='" + daInfo.EDate + "',Remark1='" + daInfo.Remark1 + "',Guid='" + daInfo.Guid + "' where DeviceID='" + DeviceId + "'";
 6         string sqlstr3 = string.Format("Insert into DynamicAccountFlow(DeviceID,UseMonth,AccuAmort,NetWorth,State,DeptID,RepairPlace,FaceID,DeviceSource,SDate,EDate,Remark1,Guid) values('{0}',{1},{2},{3},{4},{5},'{6}',{7},'{8}','{9}','{10}','{11}','{12}')", daInfo.DeviceID, daInfo.UseMonth, daInfo.AccuAmort, daInfo.NetWorth, daInfo.State, daInfo.DeptID, daInfo.RepairPlace, daInfo.FaceID, daInfo.DeviceSource, daInfo.SDate, daInfo.EDate, daInfo.Remark1, daInfo.Guid);
 7         SqlCommand comm1 = new SqlCommand(sqlstr1, conn);
 8         SqlCommand comm2 = new SqlCommand(sqlstr2, conn);
 9         SqlCommand comm3 = new SqlCommand(sqlstr3, conn);
10         conn.Open();
11         SqlTransaction trn = conn.BeginTransaction();
12         comm1.Transaction = trn;
13         comm2.Transaction = trn;
14         comm3.Transaction = trn;
15         try
16         {
17             comm1.ExecuteNonQuery();
18             comm2.ExecuteNonQuery();
19             comm3.ExecuteNonQuery();
20             trn.Commit();
21             return true;
22         }
23         catch
24         {
25             trn.Rollback();
26             return false;
27         }
28         finally
29         {
30             conn.Close();
31         }
32     }