SAP Note 18370 - ABAP/4 query: Use of credit/debit fields

Symptom:

If a total is calculated using a credit/debit field in a query, the field contents were added, regardless of the credit/debit indicator (e.g. positive values were always added). This resulted in incorrect totals, since the credit amounts must be subtracted from the total.

Cause and prerequisites

Credit/debit fields always have (positive) amounts. The +/- sign required for calculating the total can only be derived from the corresponding credit/debit indicator.
The relationship between the credit/debit field and the credit/debit indicator is not stored in the SAP System, which means that 1) the system cannot determine which fields are credit/debit fields, and 2) the system cannot determine which field is to be used as credit/ debit indicator for a credit/debit field. The query is therefore not capable of totaling credit/debit fields based on the corresponding credit/debit indicators.

Solution
If you need to calculate using credit/debit fields in queries, you must define the functional area as follows:
The credit/debit field of the logical bank is not included in the functional area. Instead, an additional field is defined with the same characteristics as the credit/debit field (use LIKE). The coding for the additional field consists of the assignment of the value of the credit/debit field, and and +/- sign is reversed, when necessary, based on the corresponding credit/debit indicator.
The additional field must be added to the functional area in place of the credit/debit indicator. The additional field enables you to calculate the correct totals in the queries.