In the design of the adapter, every effort has been made to retain compatibility with the FOCUS mainframe product. Concepts described in your FOCUS documentation become portable across environments. In some situations, however, these goals conflict with the need for pragmatic and efficient use of the relational model as implemented within the RDBMS.

In the following areas, results may be different from those you expect, or some features may not be available:

• When describing an embedded join in a multi-table Master File, the FOCUS FIELDTYPE keyword (FIELDTYPE=I) is not required for the cross-referencing field of the SQL table. The adapter ignores the keyword.
• You may not use the logical relations INCLUDES and EXCLUDES with non-FOCUS data sources in a FOCUS IF or WHERE test.
• GROUP fields are not supported.
• The FOCUS CREATE FILE command requires the DROP option in order to write over an existing table.
• HOLD FORMAT SQLengine tables created with the default name HOLD are not dropped at the end of a FOCUS session. To drop the table, issue the RDBMS DROP TABLE command.
• HOLD tables will not be overwritten when a HOLD command is issued with the same name, unless the DROP option is specified in the HOLD command.
• JOIN results (embedded or dynamic) are a function of Master Files or a JOIN specification and an OPTIMIZATION setting. All variations are discussed in Advanced Reporting Techniques.
• Since MODIFY FILE does not create a table if it does not exist, you must create the table prior to executing the MODIFY.
• Some RDBMS views may not be updated. See the documentation for your RDBMS for update restrictions concerning views.
• The maximum number of bytes per Direct SQL Passthru request is 32764 bytes.
• A COMBINE command in a MODIFY procedure may link several non-FOCUS data sources. However, you cannot use the COMBINE command to link a FOCUS data source with an RDBMS table.
• The adapter allows you to change the value of the primary key of a table with the UPDATE command in a MODIFY MATCH request. When modifying a FOCUS data source, you cannot change key field values. Also, with the adapter you can match on any field or combination of fields in a row. You need not include the full primary key.
• MODIFY does not support FOCUS alternate file views and remote segment descriptions.
• When modifying non-FOCUS data sources including RDBMS tables, you must code the keywords TRACE or ECHO on the line following the MODIFY FILE command in order to invoke tracing or echoing.
• Teradata and Oracle do not support the FOCUS field formats F and Z.
• The adapter does not support the Oracle LONG RAW data type, which has been deprecated in Oracle 8.