PHP —

Connecting to PostgreSQL

PostgreSQL has a growing fanbase. Some even say this is because the new version 8.0 finally comes in a native Windows version. However, most productive systems that use PostgreSQL are hosted on Linux or UNIX, nevertheless.

@pg_connect()

After installing the database, web-based administration software such as phpPgAdmin (http://sourceforge.net/projects/phppgadmin) or other tools such as the graphical user interface (GUI) application pgAdmin (http://www.pgadmin.org/) can be used to administer the database. Alternatively, the command-line tool can be used. To allow PHP to access the PostgreSQL installation, Windows users must load the extension with the entry extension(php_pgsql.dll) in php.ini; UNIX/Linux users configure PHP with the switch with-pgsql=/path/to/pgsql.

Then, pg_connect() connects to the data source. You have to provide a connection string that contains all important data, including host, port, name of the database, and user credentials.

Connecting to PostgreSQL

<?php
  if ($db = @pg_connect('host=localhost port=5432
   dbname=hoshmand user=postgres password=
   abc123')) {
    echo 'Connected to the database.';
    pg_close($db);
  } else {
    echo 'Connection failed.';
  }
?>

Sending SQL to PostgreSQL

pg_query()

The function pg_query() sends SQL to the PostgreSQL installation. Again, escaping potentially dangerous characters such as single quotes is a must; this can be done with the pg_escape_string() function. In this code, you see the PHP portion of the script that accepts funny (or not-so-funny) code in an HTML form and writes it to the database.

Sending SQL to PostgreSQL
<?php
  if ($db = @pg_connect('host=localhost port=5432
    dbname=hoshmand user=postgres
    password=abc123')) {
    require_once 'stripFormSlashes.inc.php';
    pg_query($db, sprintf(
      'INSERT INTO quotes (quote, author, year)
         VALUES (\'%s\', \'%s\', \'%s\')',
      pg_escape_string($_POST['quote']),
      pg_escape_string($_POST['author']),
      intval($_POST['year'])));
    echo 'Quote saved.';
    pg_close($db);
  } else {
    echo 'Connection failed.';
  }
?>

Retrieving the value in the identity column after the last INSERT statement is a bit tricky. The PostgreSQL term for such a data type is SERIAL, which automatically creates a sequence. To get the sequence's value, you can use pg_last_oid() to retrieve the oid (object id) of this value. Then, execute a SELECT id FROM quotes WHERE oid=<oid>, when <oid> is the oid you just retrieved. This finally returns the desired value.

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