<FirstName>Tim</FirstName>

<Surname>Goeke</Surname>

</Author>

<Author>

<FirstName>Thomas</FirstName>

<Surname>Lockhart</Surname>

</Author>

</AuthorGroup>

<Date>Transcribed1998-02-12</Date>

<Date>1998-08-25</Date>

</DocInfo>

<Title>ODBC Interface</Title>

<Title><acronym>ODBC</acronym> Interface</Title>

<Para>

<Note>

<Para>

Contributed by <ULink url="mailto:tgoeke@xpressway.com">Tim Goeke</ULink>

Background information originally by

<ULink url="mailto:tgoeke@xpressway.com">Tim Goeke</ULink>

</Para>

</Note>

<Para>

ODBC is an abstract API which allows you to write standard "ODBC" code,

using the ODBC API.

<acronym>ODBC</acronym> (Open Database Connectivity) is an abstract

<acronym>API</acronym>

which allows you to write standard "ODBC" applications.

<acronym>ODBC</acronym> provides a product-neutral interface

between frontend applications and database servers,

allowing a user or developer to write applications which are portable among servers.

<Sect1>

<Title>Background</Title>

<Para>

The ODBC API matches up on the backend to an ODBC compatible data source.

This could be anything from a text file to an Oracle RDBMS.

The <acronym>ODBC</acronym> <acronym>API</acronym> matches up

on the backend to an <acronym>ODBC</acronym>-compatible data source.

This could be anything from a text file to an Oracle or

<productname>Postgres</productname> <acronym>RDBMS</acronym>.

<Para>

The backend access come from ODBC drivers, or vendor specifc drivers that

allow data access.PostODBC is such a driver, along with others that are

available, such as the OpenLink ODBC drivers.

The backend access come from<acronym>ODBC</acronym> drivers, or vendor specifc drivers that

allow data access.<productname>psqlODBC</productname> is such a driver, along with others that are

available, such as the OpenLink<acronym>ODBC</acronym> drivers.

<Para>

Once you write an ODBC application, you SHOULD be able to connect to ANY

Once you write an<acronym>ODBC</acronym> application, you SHOULD be able to connect to ANY

back end database, regardless of the vendor, as long as the database schema

is the same.

<Para>

For example. you could have MS SQL Server and PostgreSQL servers which have

exactly the same data. Using ODBC, your Windows app would make exactly the

For example. you could have <productname>MS SQL Server</productname>

and <productname>Postgres</productname> servers which have

exactly the same data. Using <acronym>ODBC</acronym>, your Windows app would make exactly the

same calls and the back end data source would look the same (to the windows

app).

<para>

<ulink url="http://www.insightdist.com/">Insight Distributors</ulink> provides active and ongoing

support for the core <productname>psqlODBC</productname> distribution. They provide a

<ulink url="http://www.insightdist.com/psqlodbc/"><acronym>FAQ</acronym></ulink>, ongoing development

on the code base, and actively participate on the

<ulink url="mailto:interfaces@postgresql.org">interfaces mailing list</ulink>.

<sect1>

<title><productname>Windows</productname> Applications</title>

<Para>

In the real world, differences in drivers and the level of ODBC support

lessens the potential of ODBC:

In the real world, differences in drivers and the level of<acronym>ODBC</acronym> support

lessens the potential of<acronym>ODBC</acronym>:

<SimpleList>

<Member>

Access, Delphi, and Visual Basic all support ODBC directly.

Access, Delphi, and Visual Basic all support<acronym>ODBC</acronym> directly.

<Member>

Under C++, such as Visual C++, you can use the C++ ODBCAPI.

Under C++, such as Visual C++, you can use the C++<acronym>ODBC</acronym> <acronym>API</acronym>.

<Member>

In Visual C++, you can use the CRecordSet class, which wraps the ODBC API

set within and MFC 4.2 class. This is the easiest route if you are doing

In Visual C++, you can use the CRecordSet class, which wraps the

<acronym>ODBC</acronym> <acronym>API</acronym>

set within an MFC 4.2 class. This is the easiest route if you are doing

Windows C++ development under Windows NT.

</SimpleList>

<Para>

If I write an app for PostgreSQL can I write it using ODBC calls

to the PostgreSQL server, or is that only when another database program

If I write an app for <productname>Postgres</productname>

can I write it using <acronym>ODBC</acronym> calls

to the <productname>Postgres</productname> server, or is that only when another database program

like MS SQL Server or Access needs to access the data?

<Para>

Again, the ODBCAPI set is the way to go. You can find out more at

using.)

Again, the<acronym>ODBC</acronym> <acronym>API</acronym> set is the way to go.

Microsoft's web site or in your Visual C++ docs (if that's what you areusing.)

<Para>

Visual Basic and the other RAD tools have Recordset objects that use ODBC

Visual Basic and the other RAD tools have Recordset objects that use<acronym>ODBC</acronym>

directly to access data. Using the data-aware controls, you can quickly

link to the ODBC back end database (<Emphasis>very</Emphasis> quickly).

link to the<acronym>ODBC</acronym> back end database (<Emphasis>very</Emphasis> quickly).

<Para>

Playing around with MS Access will help you sort this out. Try using

</Para>

</Tip>

<!--

<Para>

<Tip>

<Para>

ThePostgreSQL datetime type will break MS Access.

The<productname>Postgres</productname> datetime type will break MS Access.

</Para>

</Tip>

-->

<sect1>

<title><productname>Unix</productname> Applications</title>

<para>

<productname>ApplixWare</productname> has an <acronym>ODBC</acronym> database interface

supported on at least some platforms. <productname>ApplixWare</productname> v4.4.1 has been

demonstrated under Linux with <productname>Postgres</productname> v6.4

using the <productname>psqlODBC</productname>

driver contained in the <productname>Postgres</productname> distribution.

<sect2>

<title>Configuration Files</title>

<para>

The <filename>~/.odbc.ini</filename> contains user-specified access information

for the <productname>psqlODBC</productname>

driver. The file uses conventions typical for <productname>Windows</productname>

Registry files, but despite this

restriction can be made to work.

<para>

Here is an example <filename>.odbc.ini</filename> file,

showing access information for three databases:

<programlisting>

[ODBC Data Sources]

DataEntry = Read/Write Database

QueryOnly = Read-only Database

Test = Debugging Database

Default = Postgres Stripped

[DataEntry]

ReadOnly = 0

Servername = localhost

Database = Sales

[QueryOnly]

ReadOnly = 1

Servername = localhost

Database = Sales

[Test]

Debug = 1

CommLog = 1

ReadOnly = 0

Servername = localhost

Username = tgl

Password = "no$way"

Port = 5432

Database = test

[Default]

Servername = localhost

Database = tgl

Driver = /opt/postgres/current/lib/libpsqlodbc.so

[ODBC]

InstallDir = /opt/applix/axdata/axshlib

</programlisting>

<para>

For Applix, here is an example ~/axhome/macros/login.am file:

<programlisting>

macro login

set_set_system_var@("sql_username@","tgl")

set_system_var@("sql_passwd@","no$way")

endmacro

</programlisting>

<sect1>

<title>Supported Platforms</title>

<para>

<productname>psqlODBC</productname> has been built and tested

on <productname>Linux</productname>. There have been reports of success

with FreeBSD and with Solaris.

</Chapter>

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