You create proxy points under the Rdbms Device
Extension for any of the database device types. As with
device objects in other drivers, each RdbmsNetwork device has a single Points extension.
The driver and database are installed.
The Rdbms Point Query Manager works
differently than other Point Manager views because of the way it uses
the Rdbms Points Query component. This component
(using its Sql property) filters the data to
provide the candidate records that are available for adding as proxy
points in the manager view.
Although the default view of the Rdbms Point Device Extension is the Rdbms Point
Device Ext Manager, you may often need to use the Property Sheet view and the Rdbms Query views.
In this procedure, the term “rdb Database” represents
any valid Rdbms Database Device Extension.
Expand Drivers > RdbmsNetwork in the Nav tree, expand your
rdb Database node and double-click the Points node.
The Point Device Ext Manager view
opens.
Click the New button at the bottom
of the view.
The New window opens.
Select type of RdbmsPointQuery component
to add, indicate the number of query components to add, and click Ok.
Note: If you add more than one, you can batch-edit most of the
properties to configure them all at once.
A second New window opens.Figure 1. Rdbms Point Query view
Enter the query in the Sql property.
Note: The Sql property is BFormat. You
can add BFormat syntax to the query string that processes before
the driver sends the query to the database.
Use Key Column 1 and Key
Column 2 to create a unique identifier for the point.
If you leave the key columns blank, the driver automatically
uses the first column in the row as the primary key.
Key
Column 2 is optional. Use it when you need an additional
data item to establish a unique composite key.
The key columns
you define (using the Key Column 1 and 2 properties) may not actually be primary keys, although
they often are.
An example situation where a single column
cannot uniquely identify each row in a table might be a table of fan
motor types with columns for "manufacturer", "model" and "maximum
speed". To identify each row, you need to look at both the manufacturer
and the model. These two columns would be the Key Column1 and Key
Column2 columns. Only with both of them can you identify any given
row, since individually neither column is unique.
If you need more than two key columns to specify a unique
key, add another key column slot from the RdbmsPointQuery Slot Sheet view.
Configure the other query properties and click Ok.
The driver adds the new RdbmsPointQuery component(s) under the Points Device Extension node in the Nav tree and displays them in the Rdbms Point
Device Ext Manager view.
