Index of /studiosite/lib/symfony/vendor/creole/drivers/odbc/

Creole ODBC Bridge Driver ========================= I. Overview ----------- In the text below, the word "driver" can get somewhat muddled since there are two libraries concerned here (Creole & ODBC). So, we'll use the term "bridge driver" to refer to Creole's ODBC bridge driver, and "ODBC driver" to refer to an ODBC database driver. The Creole ODBC Bridge driver provides a solution for databases which currently have no PHP-native interface. It is currently in an experimental stage of development. It has been tested with two ODBC drivers (Sequiter's CodeBase ODBC driver and the MySQL ODBC driver (as a baseline test)). To use any other ODBC drivers you may need to write your own ODBCAdapter-derived class (see below). II. ODBCAdapter --------------- Because ODBC itself is a database abstraction library, the bridge driver needed a way of hiding ODBC driver-specific behavior. The solution to this was to create an adapter layer (akin to how the Propel runtime engine works). Think of it as a sub-driver for the bridge driver. Any ODBC driver-specific behavior is handled by an ODBCAdapter-derived class. To use a specific adapter class, you specify its name via a parameter in the connection string: odbc://localhost/DSN=CodeBase;?adapter=CodeBase The string above will load the following file as the adapter to use with the bridge driver: creole/drivers/odbc/adapters/CodeBaseAdapter.php Some ODBC drivers are limited in support for various Creole features. The ODBCAdapter also provides a method for emulation of some of these missing features: -The emulatePrepareStmt() method provides a switch for enabling prepared statement emulation for drivers that do not support (or have trouble with) prepared statements. This emulation is disabled by default. -The hasLimitOffset() method provides a switch for enabling LIMIT/OFFSET emulation for drivers that do not support this. This emulation is enabled by default. The LIMIT/OFFSET emulation was borrowed from the MSSQL Creole driver. -The createResultSet() method provides a switch for enabling cached result sets. To enable this feature, return an instance of ODBCCachedResultSet in the createResultSet() method of your ODBCAdapter- derived class. This can be useful as a workaround for ODBC drivers which lack support for record count retrieval, reverse/absolute cursor scrolling, etc. In most cases, result rows are cached on-demand. So if you only read the first couple rows of a result, then only those rows will be cached. -The getIdGenerator() method provides a switch for enabling sequence emulation. This feature is enabled by default in ODBCAdapter and is implemented in the ODBCIdGenerator class. The emulation code was inspired by the PEAR::DB nextID() method. If your database supports sequences or autoincrement natively, you can return your own IdGenerator-derived class instead. Check out some of the other Creole drivers for IdGenerator examples. III. Incomplete Features ------------------------ -The database metadata classes are not fully tested/complete. Specifically, the ODBCDatabaseInfo class does not currently set the database name. There may be other problems as well. -The Creole CallableStatement class (stored procedures) is not currently implemented. No immediate plans to do this in the future, but it looks feasible. IV. Known Issues ---------------- This driver was developed using the PHP v5.0 final build. During the course of testing I uncovered several bugs in the php_odbc module. I submitted patches for these bugs, but have not yet received word that they were committed (they were just submitted this morning). If you want more details on the problems I encountered or would like a copy of the patches, please e-mail me (dlawson@masterytech.com).