[ticket/16538] Add identifiers quoting

If reserved word is used as identifier, it must be quoted.
If alias is used elsewhere in SQL statement, it must be quoted.

PHPBB3-16535
PHPBB3-16538

phpBB/phpbb/db/driver/postgres.php

@@ -497,4 +497,12 @@ class postgres extends \phpbb\db\driver\driver
 			break;
 		}
 	}
+
+	/**
+	* {@inheritDoc}
+	*/
+	function sql_quote($msg)
+	{
+		return '"' . $msg . '"';
+	}
 }