Tables (PDM)

A table is used to store data in a set of columns. Each record in the table is represented as a row, which is uniquely identified by the values in its primary key column or columns.

Tables are generally defined using the following sub-objects:

Columns - are named properties of a table that describe its characteristics (see Columns (PDM)).
Primary Keys - Uniquely identify rows through the values in the column or columns with which they are associated (see Primary, Alternate, and Foreign Keys (PDM)). Each key can generate a unique index or a unique constraint in a target database.
Indexes - Help improve search times by ordering the values in the column or columns with which they are associated (see Indexes (PDM)).
Triggers - SQL code invoked automatically whenever there is an attempt to modify data in the tables (see Triggers (PDM)).

Tables are linked together by references (see References (PDM)).

Creating a Table
You can create a table from the Toolbox, Browser, or Model menu.
Table Properties
To view or edit a table's properties, double-click its diagram symbol or Browser or list entry. The property sheet tabs and fields listed here are those available by default, before any customization of the interface by you or an administrator.
Linking a Table to an Abstract Data Type
If your DBMS supports it, PowerDesigner allows you to base tables on abstract data types (ADT), where the table uses the properties of the ADT and the ADT attributes become table columns. To link a table to an ADT, open the table property sheet to the General tab, and select the ADT (of type Object, SQLJ Object, or Structured type) in the Based On field.
Creating an XML Table or View
If your DBMS supports it, PowerDesigner allows you to create XML tables and views. An XML table does not contain columns, and instead stores an XML document. You must associate the table with a registered XML schema to validate the XML document stored in the table, and can specify a root element for the structure stored in your table.
Specifying Table Constraints
The table Check tab is initialized with the PowerDesigner %RULES% variable to generate validation rules specified on the Rules tab. You can edit the code on this tab by entering an appropriate SQL expression to supplement, modify, or replace these constraints.
Denormalizing Tables and Columns
Database normalization consists in eliminating redundancy and inconsistent dependencies between tables. While normalization is generally considered the goal of database design, denormalization, the deliberate duplication of certain data in order to speed data retrieval, may sometimes be more desirable.
PowerBuilder DataWindow Extended Attributes
When designing tables to be used in a SAP® Sybase® PowerBuilder® DataWindow, you can manage the extended attributes which PowerBuilder uses to store application-based information, such as label and heading text for columns, validation rules, display formats, and edit styles.
Displaying Column, Domain, and Data Type Information on a Table Symbol
To set display preferences for tables, select Tools > Display Preferences, and select the Table sub-category in the left-hand Category pane.
Physical Options (PDM)
Physical options are DBMS-specific parameters that specify how an object is optimized or stored in a database, and are included at the end of the object's Create statement. Physical options are defined in the DBMS definition file, and may be available for tables, columns, indexes, tablespaces, and other objects. You can specify default physical options for all objects of a particular type and for individual objects (overriding the default, if one is specified).

Parent topic: Physical Diagrams