How Changing the CA-DATADICTIONARY Database Affects Descriptor Files :: SAS/ACCESS(R) 9.3 Interface to CA-Datacom/DB: Reference

Changes That Affect the Descriptor Files

Changes to the CA-DATADICTIONARY database can affect descriptor files. You must fix the descriptors manually if changes to the CA-DATADICTIONARY database invalidate the access or view descriptors. Use the ACCESS procedure to update the access descriptor. Also, update each view descriptor with the ACCESS procedure. You receive a message if the view descriptor differs from the access descriptor. Change the view descriptor as required.

The interface view engine validates a view descriptor when it opens it. If there is a problem, a message is sent to the LOG window and processing stops. Therefore, you must change the descriptor files manually when changes to CA-DATADICTIONARY invalidate them.

When you change the CA-DATADICTIONARY database, you must re-create the access descriptor(s) with PROC ACCESS, using the same name(s).
Then you must update each view descriptor with PROC ACCESS. You get a message if the view descriptor differs from its access descriptor. Change the view descriptor as needed.
The SAS/ACCESS interface view engine does a rudimentary validation of a view descriptor when it opens it. For example, it checks the data type information. If it finds a problem, it writes a message to the log and stops.

Before changing CA-DATADICTIONARY, consider the guidelines discussed in the next three sections.

Changes That Do Not Affect Existing View Descriptors

The following changes to the CA-DATADICTIONARY database have no effect on existing view descriptors:

creating or deleting keys, unless you specified a deleted key as the Default Key.
adding new fields to a RECORD entity-occurrence.
deleting fields not referenced in any view descriptor. (Note that if an access descriptor includes the deleted item, users could eventually create a view descriptor using that item, which would be a problem.)
changing element definitions, as long as a set of one or more elements still exists that can satisfy view descriptors. The interface view engine does not require one element per view descriptor; it looks for the best set of elements for each view descriptor.
increasing the number of times a field repeats.

Changes That Might Affect Existing View Descriptors

The following changes to the CA-Datacom/DB database might have an effect on existing view descriptors: changing a field name or decreasing the number of times a field repeats.

Changes That Cause Existing View Descriptors to Fail

The following changes to the CA-Datacom/DB database cause existing view descriptors to fail:

inserting or deleting another level in repeating fields.
changing the attributes of a field. Specifically,
- You can change the pictures for character fields, but you cannot change them to a numeric type field.
- You cannot change a numeric data type to a character data type.
deleting fields that are referenced in a view descriptor.

The interface view engine validates the view against the current CA-DATADICTIONARY CA-Datacom/DB database and issues an informative error message if it detects discrepancies.