Database Interface

The database related interfaces are provided by the interface assemblies:

• Aveva.Core.Database.dll & Aveva.Core.Database.Filters.dll

This interface has the following main classes:

Namespace: Aveva.Core.Database

• DatabaseService:
  The sole purpose of this class is to open a project.

• DbAttribute:
  The class has two purposes:

  1. Instances of the class are used to identify and pass around attributes

  2. The methods allow the retrieval of metadata about an attribute, for example: type, size, Name, pseudo or not, etc. The class is valid for system attributes and User Defined Attributes (UDAs).

• DB:
  This class provides information on the opened Data Bases (DBs).

• DbElement:
  Instances of DbElement are used to identify an element. This is the main class for reading and writing to the database. The methods cover

  • element creation

  • element deletion

  • copy

  • getting/setting attributes and rules

  • navigating the DB

  • evaluating database expressions.

• DbElementType:
  The class has two purposes:

  3. Instances of the class are used to identify and pass around Element types

  4. The methods allow the retrieval of metadata about an Element type, for example: Name, description, allowed attributes and members etc.

The class is valid for system types and User Defined Element Types (UDETs).

• DbEvents:
  This class contains the mechanisms for subscribing to database events. It covers savework, getwork, undo, redo, flush, refresh, drop events plus capturing general database changes.

• DbExpression:
  Class to hold a database expression. These are the same as Programmable Macro Language (PML) 1 expressions. Methods to evaluate expressions are on the DbElement class.

• DbPseudoAttribute:
  This Class allows pseudo attribute code to be plugged in for UDAs.

• DbRule:
  Class to hold a database rule

• DbUserChanges: This is passed through by the 'database change' event. It contains a list of database changes made since the last 'database change' event was raised. Changes may be queried down to the attribute level.

• MDB:
  Methods to do operations on an Multiple DataBase (MDB), for example: savework, getwork.

• Table:
  Various classes to access the internal Dabacon tables, for example: the name table.

• Project:
  The main method is to open the MDB.

As well as the class methods there is a lot of functionality that can be accessed via pseudo attributes. The relevant pseudo attributes are listed where relevant.

The classes fall into the following groups:

• Data Model Definition Classes

• Basic database access, query and modification.

• Filters

• Iterators

• Dabacon Tables

• DBs, MDBs and Projects

• Events and pseudo attribute plugins