====== Request for Comments: PDO version 1 improvements ======
  * Version: pre alpha 0.1
  * Date: 2008-03-06
  * Author: Lukas Smith <smith@pooteeweet.org>
  * Status: Draft (Inactive)

This RFC aims to collect a set of ideas to improve PDO version 1. These ideas will hopefully end up in a set of concret feature requests and patches.

===== Introduction =====

PDO is a thin layer above native RDBMS interfaces. As such its focused on providing a unified API on the PHP level without getting too much into SQL abstraction. PDO provides a framework to make the development of RDBMS specific drivers for PDO easier.

==== Why do we need improvements to PDO? ====

PDO has become the de-facto standard for the development of PHP libraries that interact with RDBMS. As such developers have come to expect that PDO minimizes any portability differences to a minimum, while accepting that PDO will not solve most issues in the differences of the actual SQL syntax.

===== Common Misconceptions =====

A lot in PDO can be fixed without a new major version.
===== Proposal and Patch =====

  * Convenience features
    * Add a common syntax to specify the DSN along the lines of the PEAR DSN format
    * Add ability to generate a properly quoted comma separated list to be embedded in a query inside an IN() clause (see [[http://pear.php.net/package/MDB2/docs/latest/MDB2/MDB2_Driver_Datatype_Common.html#methodimplodeArray|implodeArray()]])
  * Higher level emulation features
    * Fix differences in behavior for data fetches (possibly add a compatibility mode in order to maintain BC)
    * Add ability to manage connection session aspects like charset/collation, locale (datetime/currency format)
    * Add limited sub select emulation (see [[http://pear.php.net/package/MDB2/docs/latest/MDB2/MDB2_Driver_Common.html#methodsubSelect|subSelect()]])
    * A class for administrative functionality which can come in handy for projects like phpMyAdmin. (possibly partially in userland)
    * Nested transaction emulation via SAVEPOINTs
    * Emulate scrollable cursors via buffered result sets
  * Prepared statements
    * Fix differences in when bind/prepare issues an exception for an invalid bound value/parameter.
    * Add ability to bind short binary values
    * Improve the prepared statement emulation parser to better deal with quoted strings that contain things that look like a placeholder
    * Make it possible to disable parsing and rewriting of placeholders and require the use of the given native syntax (:name, $name, ? etc.)
    * Fix the problems with ODBC prepared statements when executing procedures on all platforms.
    * Add support for PDO::PARAM_CLOB and generally work harder on making the LOB behavior more similar across the drivers (see [[http://pecl.php.net/bugs/bug.php?id=7943|Bug 7943]])
    * Add support for datatypes like float and datetime/timestamp
    * Do not force the use of prepared statements internally for simple queries without any parameters
    * Optionally only use native prepared statement for SQL injection protection, but leverage the ability of some RDBMS to pass the [http://pooteeweet.org/blog/1233 statement and the values in a single call]
  * Improve documentation
  * Add support of multiple resultsets for mssql and odbc on all platforms.
  * Add ability to retrieve the parameters set in the constructor (like DSN etc.)
  * Add ability to determine the state of the connection/transactions (as well as the ability to reconnect)
  * Make sure PDO classes implement interfaces so that frameworks can use it as a generic data access interface and implement native driver versions of it if needed (esp. PDOStatement).
  * OCI8 has some persistent connection tuning parameters like timeout, max_connections, ... Make that generic and consistent in PDO.
  * Improved Quoting
    * Consider having an attribute that sets quoting style + maybe even allow for a callback for quoting.
    * Making quoting function aware of encoding in PDO (add quoting for identifier & value)
  * Improved error handling and debugging
    * Add some better debugging hooks (like a [[bugid@44319|way to get the last submitted statement]], this is important especially when PDO does some rewriting like with prepared statements)
    * For consistency it would be good to clear errors on every call and provide facility to expose multiple notices/errors that have occurred within a transaction
    * Throw an exception if a fetch method is call on a statement that has not been executed at least once
    * Expand support for SQLSTATE error codes to ensure that all drivers return more or less compatible error codes
  * Full blown Metadata APIs ala JDBC (important for higher-level DB layers). (possibly partially in userland)
  * Test suite which DB driver authors can use for compliance testing.

==== Rejected Features ====

  * Add support for "IN (?)" type prepared placeholders. <= native prepared statement mandate that all placeholders only handle a single scalar value

==== More about PDO ====

  * http://php.net/pdo (userland manual)
  * http://php.net/internals2.pdo (internals manual)
  * http://wiki.php.net/rfc/pdonotices (rfc about database notices which can be handled by PDO)

==== References ====

  * http://pooteeweet.org/blog/1048

===== Changelog =====