Versions and Description File

The description file contains a great deal of information used to work with versions.

[Database] section

The Database section contains details of the expected (current) version of the application database, and on the method used to determine the version of an existing database.

There are two ways to determine the version of a database:

• By using an SQL query on a dedicated table (checkversion) to read it directly in the database *
  Example: select max (version) from sysadel.dbversion

• By using a service provided by a user DLL (vendordll).

* or in the 'version.ini' file with Btrieve databases.

[PDM/*] and [Data/*] sections

These sections contain the descriptions of the script sequences to run when updating a database.

Scripts are sequenced as shown below:

do_while base_version < current_version

if find_execute_pdm_script (base_version, intermediate_version) = error

exit (error)

end

if find_execute_data_script (base_version) = error

exit (error)

end

base_version = intermediate_version

redo

The system will first look for a script sequence in the specific section for the DBMS being used [PDM/<DBMS>] or [Data/<DBMS>], then in the generic section [PDM/Generic] or [Data/Generic].

The absence of a reference to a file in the sequence results in a sequence error. It is, however, possible not to provide a table description or data insertion file at a given step, by naming the file "*no_file".

Example: a description file containing the necessary information to enable the migration of a database from version 1.0 to version 2.0, with an exception for the Oracle manager.

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