Tables (PDM)

A table represents a collection of data arranged in columns and rows. Tables may contain any of the following objects:

Columns are named properties of a table that describe its characteristics (see Columns (PDM)).
Indexes are data structures associated with a table that are logically ordered by key values (see Indexes (PDM)).
Keys are columns, or combinations of columns, that uniquely identify rows in a table. Each key can generate a unique index or a unique constraint in a target database (see Keys (PDM)).
Triggers are segments of SQL code associated with tables, and stored in a database. They are invoked automatically whenever there is an attempt to modify data in associated tables (see Building Triggers and Procedures).

You can use database-specific physical options to specify physical parameters for tables and many other objects.

Creating a Table
You can create a table in any of the following ways:
Table Properties
You can modify an object's properties from its property sheet. To open a table property sheet, double-click its diagram symbol or its Browser entry in the Tables folder.
Linking a Table to an Abstract Data Type
Some DBMS like Oracle or DB2 Common Server support tables based on abstract data types (ADT). A table based on an ADT uses the properties of the ADT and the ADT attributes become table columns.
Creating an XML Table or View
Some DBMS support tables and views of XML type.
Naming a Table Constraint
A table constraint is a named check that enforces data requirements of check parameters.
Creating External Tables
You can create external tables when you need to access data in a remote table. The external table has all the properties of the remote table but it does not contain any data locally.
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 be appropriate in certain cases:
Using PowerBuilder Extended Attributes
When designing tables to be used in a 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.

Parent topic: Building Physical Diagrams