About the ODBC interface
You can access a wide variety of ODBC data sources in PowerBuilder. This
section describes what you need to know to use ODBC connections to
access your data in PowerBuilder.
ODBC drivers and data sources For a complete list of the ODBC drivers supplied
with PowerBuilder and the data sources they access, see “Database
Interfaces” in online Help.
What is ODBC?
The ODBC API
Open Database Connectivity (ODBC)
is a standard application programming interface (API) developed
by Microsoft. It allows a single application to access a variety
of data sources for which ODBC-compliant drivers exist. The application
uses Structured Query Language (SQL) as the standard data access language.
The ODBC API defines the following:
- A library of ODBC function calls that connect to the data
source, execute SQL statements, and retrieve results - A standard way to connect and log in to a DBMS
- SQL syntax based on the X/Open and SQL
Access Group (SAG) CAE specification (1992) - A standard representation for datatypes
- A standard set of error codes
Accessing ODBC data sources
Applications that provide an ODBC interface, like PowerBuilder,
can access data sources for which an ODBC driver exists. An ODBC
data source driver is a dynamic link library (DLL) that
implements ODBC function calls. The application invokes the ODBC
driver to access a particular data source.
Accessing Unicode data
Using the ODBC interface, PowerBuilder can connect, save, and
retrieve data in both ANSI/DBCS and Unicode databases but
does not convert data between Unicode and ANSI/DBCS. When
character data or command text is sent to the database, PowerBuilder sends
a Unicode string. The driver must guarantee that the data is saved
as Unicode data correctly. When PowerBuilder retrieves character data,
it assumes the data is Unicode.
A Unicode database is a database whose character set is set
to a Unicode format, such as UTF-8, UTF-16, UCS-2, or UCS-4. All
data must be in Unicode format, and any data saved to the database
must be converted to Unicode data implicitly or explicitly.
A database that uses ANSI (or DBCS) as its character set might
use special datatypes to store Unicode data. Columns with these
datatypes can store only Unicode data. Any
data saved into such a column must be converted to Unicode explicitly.
This conversion must be handled by the database server or client.
Using ODBC in PowerBuilder
What you can do
The following ODBC connectivity features are available in PowerBuilder:
- Connect
to an ASA standalone database (including the EAS Demo
DB) using the ASA ODBC driver and the ODBC interface - Create and delete local ASA databases
For instructions, see the User’s
Guide
. - Use Sybase-supplied DataDirect ODBC drivers to access
your data
For a list of the ODBC drivers supplied, see
“Database Interfaces” in online Help. - In all editions except PowerBuilder
Desktop, use Level 1 or later ODBC-compliant drivers obtained
from vendors other than Sybase to access your data
See “Obtaining ODBC drivers”. - Use Microsoft’s ODBC Data Source Administrator
to define ODBC data sources
See “Defining ODBC data sources”.
Components of an ODBC connection
How an ODBC connection is made
When you access an ODBC data source in PowerBuilder, your connection
goes through several layers before reaching the data source. It
is important to understand that each layer represents a separate
component of the connection, and that each component might come
from a different vendor.
Because ODBC is a standard API, PowerBuilder uses the same interface
to access every ODBC data source. As long as a driver is ODBC compliant, PowerBuilder can
access it through the ODBC interface to the ODBC Driver Manager.
The development environment and the ODBC interface work together
as the application component.
Figure 2-1 shows
the general components of an ODBC connection.
Component descriptions
Table 2-1 gives
the provider and a brief description of each ODBC component shown
in the diagram.
| Component | Provider | What it does |
|---|---|---|
| Application | Sybase | Calls ODBC functions to submit SQL statements, catalog requests, and retrieve results from a data source. PowerBuilder uses the same ODBC interface to access all ODBC |
| ODBC Driver Manager | Microsoft | Installs, loads, and unloads drivers for an application. |
| Driver | Driver vendor | Processes ODBC function calls, submits SQL requests to a particular data source, and returns results to an application. If necessary, translates an application’s request so |
| Data source | DBMS or database vendor | Stores and manages data for an application. Consists of the data to be accessed and its associated DBMS, operating system, and (if present) network software that accesses the DBMS. |
Types of ODBC drivers
When PowerBuilder is connected to an ODBC data source, you might
see messages from the ODBC driver that include the words single-tier or multiple-tier.
These terms refer to the two types of drivers defined by the ODBC
standard.
Single-tier driver
A single-tier ODBC driver processes
both ODBC functions and SQL statements. In other words, a single-tier
driver includes the data access software required to manage the
data source file and catalog tables. An example of a single-tier
ODBC driver is the DataDirect dBASE ODBC driver.
Multiple-tier driver
A multiple-tier ODBC driver processes
ODBC functions, but sends SQL statements to the database engine
for processing. Unlike the single-tier driver, a multiple-tier driver
does not include the data access software required to manage the
data directly.
An example of a multiple-tier ODBC driver is the Sybase ASA
driver.
Ensuring the proper ODBC driver conformance levels
You can access data in PowerBuilder Enterprise or PowerBuilder
Professional with ODBC drivers obtained from vendors other than
Sybase, such as DBMS vendors.
An ODBC driver obtained from another vendor must meet certain conformance
requirements to ensure that it works properly with PowerBuilder. This
section describes how to make sure your driver meets these requirements.
What are ODBC conformance levels?
PowerBuilder can access many data sources for which ODBC-compliant drivers
exist. However, ODBC drivers manufactured by different vendors might
vary widely in the functions they provide.
To ensure a standard level of compliance with the ODBC interface,
and to provide a means by which application vendors can determine
whether a specific driver provides the functions they need, ODBC
defines conformance levels for drivers in two areas:
- API Deals with supported ODBC function calls
- SQL grammar Deals with supported SQL statements and SQL datatypes
API conformance levels
ODBC defines three API conformance levels, in order of increasing functionality:
- Core A set of core API functions that corresponds to the functions
in the ISO Call Level Interface (CLI) and X/Open CLI specification - Level 1 Includes all Core API functions and several extended functions usually
available in an OLTP relational DBMS - Level 2 Includes all Core and Level 1 API functions and additional extended
functions
To ensure the proper ODBC driver API conformance
level:
-
Sybase recommends that the ODBC drivers
you use with PowerBuilder meet Level 1 or higher API
conformance requirements. However, PowerBuilder might also work with
drivers that meet Core level API conformance requirements.
SQL conformance levels
ODBC defines three SQL grammar conformance levels, in order
of increasing functionality:
- Minimum A set of SQL statements and datatypes that meets a basic level of
ODBC conformance - Core Includes all Minimum SQL grammar and additional statements and
datatypes that roughly correspond to the X/Open and SAG
CAE specification (1992) - Extended Includes all Minimum and Core SQL grammar and an extended
set of statements and datatypes that support common DBMS extensions
to SQL
To ensure the proper ODBC driver SQL conformance
level:
-
Sybase recommends that the ODBC drivers
you use with PowerBuilder meet Core or higher SQL
conformance requirements. However, PowerBuilder might also work with
drivers that meet Minimum level SQL conformance requirements.
Obtaining ODBC drivers
Two sources
There are two ways that you can obtain ODBC drivers for use
with PowerBuilder:
- From Sybase (recommended) Install one or more of the ODBC drivers shipped with PowerBuilder.
You can do this when you first install PowerBuilder, or later. - From another vendor PowerBuilder Enterprise and PowerBuilder Professional let
you access data with any Level 1 or higher ODBC-compliant
drivers obtained from a vendor other than Sybase. In most cases,
these drivers will work with PowerBuilder.
Using ODBC drivers with PowerBuilder Desktop
Using ODBC drivers that come with Desktop
If you are using PowerBuilder Desktop, you can access data
using only the ODBC drivers that are shipped with the product. For
a list of these drivers, see ODBC drivers in the online Help. Unlike
PowerBuilder Enterprise and PowerBuilder Professional, with PowerBuilder
Desktop you cannot use an ODBC driver obtained
from another vendor.
Using existing Microsoft ODBC drivers
If you already have version 2.0 or later of any of the following
Microsoft ODBC drivers installed and properly configured, you can use
these drivers with PowerBuilder Desktop to connect to your data
source:
- Microsoft Access (*.MDB)
- Microsoft Btrieve (*.DDF)
- Microsoft dBASE (*.DBF)
- Microsoft Excel (*.XLS)
- Microsoft FoxPro (*.DBF)
- Microsoft Paradox (*.DB)
- Microsoft Text (*.CSV, *.TXT)
Using DataDirect drivers is recommended PowerBuilder Desktop comes with DataDirect ODBC drivers for
several of these data sources. You should use the DataDirect drivers
whenever possible to access these data sources.
Getting help with ODBC drivers
To ensure that you have up-to-date and accurate information
about using your ODBC driver with PowerBuilder, get help as needed
by doing one or more of the following:
| To get help on | Do this |
|---|---|
| Using the ODBC Data Source Administrator | Click the Help button on each tab. |
| Completing the ODBC setup dialog box for your driver |
Click the Help button (if present) in the ODBC setup dialog box for your driver. |
| Using ASA | See the ASA documentation. |
| Using an ODBC driver obtained from a vendor other than Sybase |
See the vendor’s documentation for that driver. |
| Troubleshooting your ODBC connection | Check for a technical document that describes how to connect to your ODBC data source. Updated information about connectivity issues is available on the Sybase Customer Service and Support Web site . |