Natively Connect to Greenplum Data in PHP



Create PHP applications on Linux/UNIX machines with connectivity to Greenplum data. Leverage the native support for ODBC in PHP.

Drop the CData ODBC Driver for Greenplum into your LAMP or WAMP stack to build Greenplum-connected Web applications. This article shows how to use PHP's ODBC built-in functions to connect to Greenplum 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 Greenplum ...

List the Defined Data Source(s)

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

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

cdata.odbc.greenplum.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 Greenplum, 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 default database for the authenticate user is used.

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

[CData Greenplum Source] Driver = CData ODBC Driver for Greenplum Description = My Description User = user Password = admin Database = dbname 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 Greenplum by calling the odbc_connect or odbc_pconnect methods. To close connections, use odbc_close or odbc_close_all.

$conn = odbc_connect("CData ODBC Greenplum 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.

$conn = odbc_pconnect("CData ODBC Greenplum Source","user","password"); ... odbc_close($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 Greenplum 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 Greenplum Source","user","password"); $query = odbc_exec($conn, "SELECT Freight, ShipName FROM Orders WHERE ShipCountry = USA");

Process Results

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

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

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

$conn = odbc_connect("CData ODBC Greenplum 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 Greenplum-specific adaptations of the PHP community documentation for all ODBC functions.

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The Greenplum ODBC Driver is a powerful tool that allows you to connect with Greenplum, directly from any applications that support ODBC connectivity.

Access Greenplum databases from virtually anywhere through a standard ODBC Driver interface.