As we learnt in SAP SD Training, a Transaction is uniquely idenfied in the database using a Transaction Number / Document Number. In SAP CRM this uniqueness is not driven by the document number, but by SAP GUID. An SAP GUID is a unique field generated by SAP which will essentially guarantee a big unique alpha-numeric numer that can act as a primary key for the database tables.
As you can see from the basic ORDER table – CRMD_ORDERADM_H, there are two leads with the same Lead Number of #476, but what differentiates the table rows is the GUID. GUIDs are created using the FM – GUID_CREATE.
What intrigues the folks from the core SAP ECC system is that over there there is no concept of GUID, whereas in SAP CRM this becomes the primary key. This was necessitated by a number of problems – Mostly related to the fact that CRM is generally not a master data system and also the fact that CRM is essentially built to interact with mobile clients as well which are not necessarily connected to the server. Let’s consider the following scenarios.
1. A mobile order (say Txn Type – ZTA) was taken by a field rep on his laptop and the laptop generated an order # 1234. This number was generated without consulting the Server and might not reflect the current number range scenarios for the Txn type ZTA. Now what happens when the fields sales rep connects to the server at the end of his day and tries to sync the data ? If the Order # was the only primary key, obviously you are in trouble – especially since its the primary field. So SAP CRM came up with the concept of GUID which uniquely identifes the transaction in the system no matter what.
2. Also, it is not always the case that all transactions need to be created in SAP CRM. For example, regular sales orders can be created in SAP SD whereas Service Orders, leads and opportunities could be created in SAP CRM. Since data needs to be synchronized between the two systems – this could lead to potential issues. Although there are mitigatory mechanisms for situations like this ( Like creating leading systems, making number ranges external in receiving system etc ) SAP has to plan for its own contingencies and GUID is the key for it.