4.2.1 LANSA File Concepts
A file is a database table in which records can be retrieved, added, changed or deleted. In IBM i terminology, a file may be a physical file or a logical file. Logical files are also known as views in some database terminology.
To create a file, LANSA uses a Repository-based File Definition. This file definition is a database independent definition of the file characteristics.
A file definition contains:
- The real field in the file that make up the format of the file records. Some keys may be nominated as keys to the file.
- 4.3 Logical View Development of the file that are required. The logical views may contain select/omit criteria.
In addition the LANSA file definition may also contain:
- 4.4 Virtual Field Development that are fields which are not actually present in the database file but are derived from fields that are in it. Hence the name virtual. These fields appear as if they were in the file, even though they are not.
- 4.5 File Rules & Triggers Development that are to be performed on fields when records are added, updated or deleted.
- 4.6 Access Route Development from the current file to other files in the system. This facility allows users to access a complete database without having a detailed knowledge of its structure.
- 4.7 Predetermined Join Field Development which use the current file's access routes to retrieve information from related files.
- 4.8 Batch Control Development which specifies other files in the system that contain batch, control or summary totals of information in the current file. LANSA will ensure that the summary or control information in other files is automatically maintained.
Some points to note about working with file definitions are:
- The file definition name and actual physical file name are always the same. When LANSA requests that the name of a file definition be supplied, specify the name of the physical file (as opposed to the name of any associated logical views/ files).
- The allowed field types in a file are determined by the partition settings. For more details, refer to RDML and RDMLX Partition Concepts in the .
- Within the LANSA System, logical views/files are considered to be part of the file definition.
- The file definition contains the attributes of the associated physical file and all associated logical views/files.