Natively Connect to PostgreSQL Data in PHP via ODBC (Linux)

Drop the CData ODBC Driver for PostgreSQL into your LAMP or WAMP stack to build PostgreSQL-connected Web applications. This article shows how to use PHP's ODBC built-in functions to connect to PostgreSQL data, execute queries, and output the results.

Using the CData ODBC Drivers on a UNIX/Linux Machine

The CData ODBC Drivers are supported in various Red Hat-based and Debian-based systems, including Ubuntu, Debian, RHEL, CentOS, and Fedora. There are also several libraries and packages that are required, many of which may be installed by default, depending on your system. For more information on the supported versions of Linux operating systems and the required libraries, please refer to the "Getting Started" section in the help documentation (installed and found online).

Installing the Driver Manager

Before installing the driver, check that your system has a driver manager. For this article, you will use unixODBC, a free and open source ODBC Driver manager that is widely supported.

For Debian-based systems like Ubuntu, you can install unixODBC with the APT package manager:

$ sudo apt-get install unixodbc unixodbc-dev

For systems based on Red Hat Linux, you can install unixODBC with yum or dnf:

$ sudo yum install unixODBC unixODBC-devel

The unixODBC driver manager reads information about drivers from an odbcinst.ini file and about data sources from an odbc.ini file. You can determine the location of the configuration files on your system by entering the following command into a terminal:

$ odbcinst -j

The output of the command will display the locations of the configuration files for ODBC data sources and registered ODBC drivers. User data sources can only be accessed by the user account whose home folder the odbc.ini is located in. System data sources can be accessed by all users. Below is an example of the output of this command:

DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/myuser/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

Installing the Driver

You can download the driver in standard package formats: the Debian .deb package format or the .rpm file format. Once you have downloaded the file, you can install the driver from the terminal.

The driver installer registers the driver with unixODBC and creates a system DSN, which can be used later in any tools or applications that support ODBC connectivity.

For Debian-based systems like Ubuntu, run the following command with sudo or as root:

$ dpkg -i /path/to/package.deb

For Red Hat systems or other systems that support .rpms, run the following command with sudo or as root:

$ rpm -i /path/to/package.rpm

Once the driver is installed, you can list the registered drivers and defined data sources using the unixODBC driver manager:

List the Registered Driver(s)

$ odbcinst -q -d
CData ODBC Driver for PostgreSQL
...

List the Defined Data Source(s)

$ odbcinst -q -s
CData PostgreSQL Source
...

To use the CData ODBC Driver for PostgreSQL with unixODBC, ensure that the driver is configured to use UTF-16. To do so, edit the INI file for the driver (cdata.odbc.postgresql.ini), which can be found in the lib folder in the installation location (typically /opt/cdata/cdata-odbc-driver-for-postgresql), as follows:

cdata.odbc.postgresql.ini

...

[Driver]
DriverManagerEncoding = UTF-16

Modifying the DSN

The driver installation predefines a system DSN. You can modify the DSN by editing the system data sources file (/etc/odbc.ini) and defining the required connection properties. Additionally, you can create user-specific DSNs that will not require root access to modify in $HOME/.odbc.ini.

To connect to PostgreSQL, set the Server, Port (the default port is 5432), and Database connection properties and set the User and Password you wish to use to authenticate to the server. If the Database property is not specified, the data provider connects to the user's default database.

SSH Connectivity for PostgreSQL

You can use SSH (Secure Shell) to authenticate with PostgreSQL, whether the instance is hosted on-premises or in supported cloud environments. SSH authentication ensures that access is encrypted (as compared to direct network connections).

SSH Connections to PostgreSQL in Password Auth Mode

To connect to PostgreSQL via SSH in Password Auth mode, set the following connection properties:

• User: PostgreSQL User name
• Password: PostgreSQL Password
• Database: PostgreSQL database name
• Server: PostgreSQL Server name
• Port: PostgreSQL port number like 3306
• UserSSH: "true"
• SSHAuthMode: "Password"
• SSHPort: SSH Port number
• SSHServer: SSH Server name
• SSHUser: SSH User name
• SSHPassword: SSH Password

SSH Connections to PostgreSQL in Public Key Auth Mode

To connect to PostgreSQL via SSH in Password Auth mode, set the following connection properties:

• User: PostgreSQL User name
• Password: PostgreSQL Password
• Database: PostgreSQL database name
• Server: PostgreSQL Server name
• Port: PostgreSQL port number like 3306
• UserSSH: "true"
• SSHAuthMode: "Public_Key"
• SSHPort: SSH Port number
• SSHServer: SSH Server name
• SSHUser: SSH User name
• SSHClientCret: the path for the public key certificate file

/etc/odbc.ini or $HOME/.odbc.ini

[CData PostgreSQL Source]
Driver = CData ODBC Driver for PostgreSQL
Description = My Description
User = postgres
Password = admin
Database = postgres
Server = 127.0.0.1
Port = 5432

For specific information on using these configuration files, please refer to the help documentation (installed and found online).

Establish a Connection

Open the connection to PostgreSQL by calling the odbc_connect or odbc_pconnect methods. To close connections, use odbc_close or odbc_close_all.

$conn = odbc_connect("CData ODBC PostgreSQL Source","user","password");

Connections opened with odbc_connect are closed when the script ends. Connections opened with the odbc_pconnect method are still open after the script ends. This enables other scripts to share that connection when they connect with the same credentials. By sharing connections among your scripts, you can save system resources and queries execute faster.

$conn = odbc_pconnect("CData ODBC PostgreSQL Source","user","password");
...
odbc_close($conn); //persistent connection must be closed explicitly

Create Prepared Statements

Create prepared statements and parameterized queries with the odbc_prepare function.

$query = odbc_prepare($conn, "SELECT * FROM Orders WHERE ShipCountry = ?");

Execute Queries

Execute prepared statements with odbc_execute.

$conn = odbc_connect("CData ODBC PostgreSQL Source","user","password");
$query = odbc_prepare($conn, "SELECT * FROM Orders WHERE ShipCountry = ?");
$success = odbc_execute($query, array('USA'));
 

Execute nonparameterized queries with odbc_exec.

$conn = odbc_connect("CData ODBC PostgreSQL Source","user","password");
$query = odbc_exec($conn, "SELECT ShipName, ShipCity FROM Orders");
 

Process Results

Access a row in the result set as an array with the odbc_fetch_array function.

$conn = odbc_connect("CData ODBC PostgreSQL data Source","user","password");
$query = odbc_exec($conn, "SELECT ShipName, ShipCity FROM Orders");
while($row = odbc_fetch_array($query)){
 echo $row["ShipName"] . "\n";
}

Display the result set in an HTML table with the odbc_result_all function.

$conn = odbc_connect("CData ODBC PostgreSQL data Source","user","password");
$query = odbc_prepare($conn, "SELECT * FROM Orders WHERE ShipCountry = ?");
$success = odbc_execute($query, array('USA'));
if($success)
 odbc_result_all($query);

More Example Queries

You will find complete information on the SQL queries supported by the driver in the help documentation. The code examples above are PostgreSQL-specific adaptations of the PHP community documentation for all ODBC functions.