In BAPIs that cause database changes (for example, Change() and Create() BAPIs), you must be able to distinguish between parameter fields that are to be modified (change-relevant fields) and parameter fields that are to remain unmodified.

Using an initial value is no solution because an initial value could also represent a valid new value. Also, in the ABAP programming language as well as on other development platforms, the value "NULL" should not be assigned to a data type to indicate an empty field.

Standardized change parameters are used to identify fields with modified values in Change() and Create() BAPIs. You can do this in two ways:

• Flagging Fields to Identify Fields Containing Modified Values
• Comparing Fields to Identify Fields Containing Modified Values

In this approach parameter fields containing modified values are identified by including a flag in an additional "change parameter".

• An additional change parameter must be created with the same number of fields and the same field names for every parameter in the BAPI containing modified field values.
• When the BAPI is called, the fields in the additional change parameter whose counterparts in the corresponding parameter contain modifications, must be marked with an update flag.

This way the BAPI can identify both modified and unmodified fields in the parameter.

Follow the conventions below when you create change parameters to identify modified fields:

• The name of the additional change parameter consists of the parameter name with the suffix "X". For instance, if the parameter is called EquiSales, the name of the additional change parameter is EquiSalesX.
• The additional change parameter must contain exactly the same number of fields and the same field names as the parameter. You must use the data element BAPIUPDATE (CHAR 1) as the data element for the update fields. This can have the following values:

• 'X'

• ' ' (no value)

• If the parameter is a table, the additional change parameter must also be a table.

In this approach fields containing modified values are identified by comparing two parameters, one containing the current valid data and the other the new, modified data.

When the Change() BAPI is called, the current data in the database and the new, modified data must be entered in the corresponding parameters. The current data set can be transferred, for instance, from a GetDetail() BAPI that has been called.

The following comparisons can be made:

• The current data can first be checked against the database contents to ascertain whether it has changed in the meantime. This way any database changes made between the time the data was read by the GetDetail() BAPI and the time the database is updated can be identified.
• The data in both the parameters can be compared field by field. If the data in two corresponding fields is different, the relevant values must be transferred from the parameter with the new data.

Note the following when you are comparing fields containing modified data.

• A calling program must be able to provide data in all the parameter fields of the Change() BAPI. For this reason, the parameter fields of the Change() BAPI must be exactly the same as the fields in the GetDetail() BAPI of the same business object type.
• The names of the parameters to be compared must be the same, but the parameter containing the modified data must also have the suffix ‘New’.

• Both parameters must have exactly the same fields and the same structure.

1. Entering data from the relevant GetDetail() BAPI in the parameter EquiSales.
2. Initializing the parameter EquiSalesNew with the values from the parameter EquiSales.
3. Modifying the required parameter values in the parameter EquiSalesNew, for example: EquiSalesNew-Distr_Chan='EN'.

The table below compares the two ways of identifying fields containing modified values in BAPIs, as described above, and should help you decide which way suits your requirements best.