OpenEdge Data Management: DataServer for Microsoft SQL Server

Initial Programming Considerations
ABL issues
2–52
The following sections describe how to use various ABL statements in DataServer applications
and list which ABL statements and functions the DataServer does not support.
ROWID function
The ROWID data type provides a unique record identifier that is compatible across OpenEdge and
MS SQL Server databases. Applications that use the ROWID function behave in the same way
whether they access records in an OpenEdge databases or in a MS SQL Server data source. The
ROWID function is more consistent than RECID across data sources, since RECID cannot guarantee
uniqueness. Progress Software Corporation recommends that you replace the RECID function
with ROWID in existing applications.
The DataServer supports the ROWID function for MS SQL Server data source tables that have a
unique index. The DataServer utilities use an index that meets this criterion to provide values
for the ROWID function. If you build your schema holder using the OpenEdge DB to MS SQL
Server utility and you select the Create RECID field option, it is automatically designated as
the ROWID index. However, if you do not create the RECID field, you can select a unique index
to support ROWID. See the “Defining the ROWID” section on page 7–35 for instructions.
Note: Starting with OpenEdge Release 10.1B, the default external representation of ROWID
enables the MS SQL Server Dataserver to use a 64-bit integer value for ROWID. Using
an integer value to define ROWID is not required, but rather an option to efficiently
represent ROWID as a numeric binary value. The MS SQL Server DataServer supports
the INT64 data type to emulate ROWID expansion support in this use.
The ROWID value in a MS SQL Server data source differs from the ROWID value in an OpenEdge
database if you use the unique index method in the following ways:
• In an OpenEdge database, you can create a ROWID without creating a record. In DataServer
applications, creating a ROWID creates a record. The following statement illustrates the
difference in behavior:
CREATE customer.
a = ROWID(customer).
The DataServer creates a customer record using default values.
• The ROWID changes if the value of the unique keys in the designated index changes.
• The DataServer considers a single instance of the Unknown value (?) to be unique, so it is
possible to have a ROWID with the Unknown value (?). However, the OpenEdge ROWID
function fails if you search for an Unknown value (?), because an OpenEdge ROWID will
never have the Unknown value (?). For example, the following FIND statement fails even
if there is a row with the Unknown value (?) in the designated column:
FIND customer WHERE ROWID(customer) EQ ?.