Connect a PHP client to a PolarDB cluster - PolarDB

Connect a PHP application to a PolarDB for Oracle cluster using the pgsql extension.

Prerequisites

Before you begin, ensure that you have:

A database account on your PolarDB cluster. See Create a database account.
The IP address of your application host added to the cluster whitelist. See Configure a whitelist for a cluster.

Set up the environment

Windows

Download and install WampServer.
Enable the PostgreSQL extension in php.ini. Open php.ini and uncomment the following lines by removing the leading semicolons: Before:
```
;extension=php_pgsql.dll
;extension=php_pdo_pgsql.dll
```
After:
```
extension=php_pgsql.dll
extension=php_pdo_pgsql.dll
```
Copy libpq.dll from C:\wamp\bin\php\php5.6.40 to C:\windows\system32\.
The path php5.6.40 is an example. Use the directory that matches your installed PHP version.
Restart the Apache service.

Linux

Install the PHP PostgreSQL driver:
```
sudo yum install php-pgsql.x86_64
```
Open php.ini:
```
vim /etc/php.ini
```
Add the following line:
```
extension=php_pgsql.so
```

Connect to PolarDB

Replace the placeholders in the following script with your actual values before running it.

Placeholder	Description	Example
`<cluster-endpoint>`	The endpoint of your PolarDB cluster. See View or apply for an endpoint.	`pc-xxxx.polardb.aliyuncs.com`
`<port>`	The port of your PolarDB cluster. Default: `1521`.	`1521`
`<database-name>`	The name of the database to connect to.	`mydb`
`<username>`	The database account username.	`myuser`
`<password>`	The database account password.	—

The script uses pg_connect() to establish the connection, pg_query() to run a SQL query, pg_fetch_all() to retrieve the results, and pg_close() to close the connection. If any step fails, pg_last_error() returns the error details.

<?php
$host        = "host=<cluster-endpoint>";
$port        = "port=<port>";
$dbname      = "dbname=<database-name>";
$credentials = "user=<username> password=<password>";

$db = pg_connect("$host $port $dbname $credentials");
if (!$db) {
    echo "Error: Unable to open database\n";
    echo pg_last_error();
    exit;
}

echo "Connected successfully\n";

$sql = "SELECT * FROM pg_roles;";
$ret = pg_query($db, $sql);
if (!$ret) {
    echo pg_last_error($db);
} else {
    echo "Query executed successfully\n";
    $results = pg_fetch_all($ret);
    print_r($results);
}

pg_close($db);
?>

What's next

For the full list of PHP PostgreSQL functions, see the PHP pgsql extension documentation.