Generate HL7 message format

Question

I'd like to create a C# program that generate the HL7 messages foramt by rooping through the table in database.
I have two tables: Patient and lab result.

I am trying to looping through these tables and generate the HL7 messages. some fields are default and some fields are comming from the database.
Please see the comments

For example,

Here is the data in the tables:
PId                 lastname firstname
19191919       John        Rick

Test         Result    name
URR        79          John, rick
HGB       11.2        John, rick

and the HL 7 message that generate by the program should look like:

MSH|^&\~|NAPPY|||4|20060705003913||DFT^P03|0|P|2.2
EVN|P03|20060705003913||OVR
PID|||19191919||John^Rick  -- -----------> Patient Id 19191919 , and last and first name John^Rick comes from the dataabse
OBX||ST|URR^URR||11||||||R ------------>Lab value: 11 comes from the database
OBX||ST|HCT^HGB||79.2||||||R ----------------->Lab value:79.2 comes from the database
FT1||||20060601||C|ZZ^Load Lab Results^^N^N|||1|||A230||||||586.6 ----------------> A230 comes from the database
BTS|1 -------------------> count of message in file
FTS|1

what is the best way to do this? can you show me some examples?