Introduction
Customers often have to change the standard SAP objects in order to meet their own specific requirements. They might want too add few extra fields to the standard SAP development. Which is necessary from their specific business process point of view. This fields might get updated in underlying Standard SAP tables or customer database table and ultimately serve the business purpose .
But this change might affect the further BAPI implementations. This is because BAPIs are designed to implement SAP standard business processes through a predefined standard interface. i.e. It's import and export parameters for any BAPI are fixed. So addition of new customer fields has absolutely nothing to do with this predefined BAPI interface. This because these fields are added to SAP database tables through some other Enhancements and not directly through respective BAPI. So executing BAPI with the same import and export parameter is not sufficient. We have to pass an extra information about newly added fields. This information is passed to the BAPI using BAPI table extension. These extension tables acts as container tables. The naming convention for BAPI table extensions is BAPI_TE_<table_name>.
For example, assume that there is an extra information that we want to save to the database while creating a new purchase order. i.e. Prepared By, Checked By, Approved By. Here the customer first creates a data structure that contains the customer-specific fields. In our example, it is CI_EKKODB. This structure is included in both the database table and the BAPI table extension. This ensures that the enhancements to the database table and in the table extension are always identical.
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Also, an extension parameter (ExtensionIn) in the BAPI interface is used to pass on the enhancements to the BAPI in container format. This extension parameter is always based on data structure BAPIPAREX. Using this parameter BAPI understands the format of the data to be passed.
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Here, the STRUCTURE refers to the name of the BAPI table extension though which extra information is to be sent. Whereas VALUEPART1-VALUEPART4 values that will be inserted in the additional table fields along with the table key field. Key field, here, purchase_order_no is the extra information that needs to be passed to know the line in the database table where the data record needs to be be written.