Add Postgresql support

vendor/PicoDb/Drivers/Postgres.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace PicoDb;
+
+class Postgres extends \PDO {
+
+    private $schema_table = 'schema_version';
+
+
+    public function __construct(array $settings)
+    {
+        $required_atttributes = array(
+            'hostname',
+            'username',
+            'password',
+            'database',
+        );
+
+        foreach ($required_atttributes as $attribute) {
+            if (! isset($settings[$attribute])) {
+                throw new \LogicException('This configuration parameter is missing: "'.$attribute.'"');
+            }
+        }
+
+        $dsn = 'pgsql:host='.$settings['hostname'].';dbname='.$settings['database'];
+
+        parent::__construct($dsn, $settings['username'], $settings['password']);
+
+        if (isset($settings['schema_table'])) {
+            $this->schema_table = $settings['schema_table'];
+        }
+    }
+
+
+    public function getSchemaVersion()
+    {
+        $this->exec("CREATE TABLE IF NOT EXISTS ".$this->schema_table." (version SMALLINT DEFAULT 0)");
+
+        $rq = $this->prepare('SELECT version FROM '.$this->schema_table.'');
+        $rq->execute();
+        $result = $rq->fetch(\PDO::FETCH_ASSOC);
+
+        if (isset($result['version'])) {
+            return (int) $result['version'];
+        }
+        else {
+            $this->exec('INSERT INTO '.$this->schema_table.' VALUES(0)');
+        }
+
+        return 0;
+    }
+
+
+    public function setSchemaVersion($version)
+    {
+        $rq = $this->prepare('UPDATE '.$this->schema_table.' SET version=?');
+        $rq->execute(array($version));
+    }
+
+
+    public function getLastId()
+    {
+        $rq = $this->prepare('SELECT LASTVAL()');
+        $rq->execute();
+        return $rq->fetchColumn();
+    }
+
+
+    public function escapeIdentifier($value)
+    {
+        return $value;
+    }
+}