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Step 6 - One to Many Relationships

So far you have been dealing with HL7 messages that have very simple, flat segment grammars. However, things get a little more complicated when you want to map data from repeating segments (or repeating groups of segments).

In this tutorial, you will map data from a repeating segment of a message into a table. You will then relate the segment data contained in this table to the message data contained in another table. This is called a One to many or 1-n relationship.

You will create a sample 1-n relationship by adding the ability to process Patient Observation messages. These messages contain one or more ORU segments. To process these messages, you will:

• Create a message definition for the Patient Observation message;
• Create a segment grammar and table grammar for the message definition;
• Map data from the repeating segment to a table;
• Use Python scripts to retrieve the Patient ID from the PID segment and store it in this table. This Patient ID will serve as a key to associate this table with the other tables you have created.