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

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

List the Defined Data Source(s)

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

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

cdata.odbc.alloydb.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.

The following connection properties are usually required in order to connect to AlloyDB.

• Server: The host name or IP of the server hosting the AlloyDB database.
• User: The user which will be used to authenticate with the AlloyDB server.
• Password: The password which will be used to authenticate with the AlloyDB server.

You can also optionally set the following:

• Database: The database to connect to when connecting to the AlloyDB Server. If this is not set, the user's default database will be used.
• Port: The port of the server hosting the AlloyDB database. This property is set to 5432 by default.

Authenticating with Standard Authentication

Standard authentication (using the user/password combination supplied earlier) is the default form of authentication.

No further action is required to leverage Standard Authentication to connect.

Authenticating with pg_hba.conf Auth Schemes

There are additional methods of authentication available which must be enabled in the pg_hba.conf file on the AlloyDB server.

Find instructions about authentication setup on the AlloyDB Server here.

Authenticating with MD5 Authentication

This authentication method must be enabled by setting the auth-method in the pg_hba.conf file to md5.

Authenticating with SASL Authentication

This authentication method must be enabled by setting the auth-method in the pg_hba.conf file to scram-sha-256.

Authenticating with Kerberos

The authentication with Kerberos is initiated by AlloyDB Server when the ∏ is trying to connect to it. You should set up Kerberos on the AlloyDB Server to activate this authentication method. Once you have Kerberos authentication set up on the AlloyDB Server, see the Kerberos section of the help documentation for details on how to authenticate with Kerberos.

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

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

$conn = odbc_connect("CData ODBC AlloyDB 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.

$conn = odbc_pconnect("CData ODBC AlloyDB Source","user","password");
...
odbc_close($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 AlloyDB 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 AlloyDB Source","user","password");
$query = odbc_exec($conn, "SELECT ShipName, ShipCity 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 AlloyDB data Source","user","password");
$query = odbc_exec($conn, "SELECT ShipName, ShipCity FROM Orders WHERE ShipCountry = 'USA'");
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 AlloyDB 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 AlloyDB-specific adaptations of the PHP community documentation for all ODBC functions.