OpenEdge Data Management: DataServer for Microsoft SQL Server

RDBMS Stored Procedure Details
3–18
However, a disadvantage in using the proc-text-buffer technique is that it is much more
difficult to manipulate the data after you receive it as it requires parsing the data. To act on
anything but CHARACTER data, you must extract the data from the buffer and convert it to its
original data type before you can use it.
Defining a view to use as a buffer
As an alternative to using the OpenEdge buffer proc–text–buffer definition, you can define a
view in the data source that can serve as a buffer allowing you to retrieve database results in
their original data types. However, keep in mind that using views creates a database dependency
beyond the stored procedure itself.
Technique to define a view to use as a buffer
While a stored procedure can include multiple SQL statements, a buffer that you define contains
the format of only a single results set. You need to define multiple views to accommodate
multiple results sets.
To define a buffer:
1. Define a view in the MS SQL Server data source with the following characteristics:
• The naming convention _BUFFER_buffername
• The same number of columns and data types that the stored procedure returns in the
results set
• The columns in the order that the stored procedure returns them
For example, to return two columns with two types of values, an integer and a character
string, use a SQL utility to define the following view in the data source:
CREATE VIEW _BUFFER_custlist AS SELECT customer.cust_num,
customer.name FROM customer WHERE 1 = 0
GO
Notice that these views are defined to ensure that they never return any results. This helps
to indicate that the purpose of the view is its buffer content and not its SQL capabilities. It
is not necessary to define views that you will use as buffers this way, but it does allow you
to distinguish quickly between views and buffers.
2. Update your schema image using the Update/Add Table Definitions DataServer utility.
The utility adds the view to the list of accessible objects in the schema holder. The
DataServer defines the view as a buffer that OpenEdge can use. (See the “Updating a
schema holder” section on page 7–11 for instructions on using this utility.)
Assessing result sets obtained by defining a view as buffer technique
The buffer in the previous procedure defines two returned values for a stored procedure—an
INTEGER and a CHARACTER value—in that order. If the data types do not match those returned by
the stored procedure, the procedure returns more than two values, or returns the values in a
different order than you specified, you receive a run-time error.