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Annotation of embedaddon/php/ext/pdo/README, revision 1.1

1.1     ! misho       1: $Id: README 242949 2007-09-26 15:44:16Z cvs2svn $
        !             2: 
        !             3: PHP Data Objects
        !             4: ================
        !             5: 
        !             6: Concept: Data Access Abstraction
        !             7: 
        !             8: Goals:
        !             9: 
        !            10: 1/  Be light-weight
        !            11: 2/  Provide common API for common database operations
        !            12: 3/  Be performant
        !            13: 4/  Keep majority of PHP specific stuff in the PDO core (such as persistent
        !            14:     resource management); drivers should only have to worry about getting the
        !            15:     data and not about PHP internals.
        !            16: 
        !            17: 
        !            18: Transactions and autocommit
        !            19: ===========================
        !            20: 
        !            21: When you create a database handle, you *should* specify the autocommit
        !            22: behaviour that you require.  PDO will default to autocommit on.
        !            23: 
        !            24: $dbh = new PDO("...", $user, $pass, array(PDO_ATTR_AUTOCOMMIT => true));
        !            25: 
        !            26: When auto-commit is on, the driver will implicitly commit each query as it is
        !            27: executed.  This works fine for most simple tasks but can be significantly
        !            28: slower when you are making a large number of udpates.
        !            29: 
        !            30: $dbh = new PDO("...", $user, $pass, array(PDO_ATTR_AUTOCOMMIT => false));
        !            31: 
        !            32: When auto-commit is off, you must then use $dbh->beginTransaction() to
        !            33: initiate a transaction.  When your work is done, you then call $dbh->commit()
        !            34: or $dbh->rollBack() to persist or abort your changes respectively.  Not all
        !            35: databases support transactions.
        !            36: 
        !            37: You can change the auto-commit mode at run-time:
        !            38: 
        !            39: $dbh->setAttribute(PDO_ATTR_AUTOCOMMIT, false);
        !            40: 
        !            41: Regardless of the error handling mode set on the database handle, if the
        !            42: autocommit mode cannot be changed, an exception will be thrown.
        !            43: 
        !            44: Some drivers will allow you to temporarily disable autocommit if you call
        !            45: $dbh->beginTransaction().  When you commit() or rollBack() such a transaction,
        !            46: the handle will switch back to autocommit mode again.  If the mode could not
        !            47: be changed, an exception will be raised, as noted above.
        !            48: 
        !            49: When the database handle is closed or destroyed (or at request end for
        !            50: persistent handles), the driver will implicitly rollBack().  It is your
        !            51: responsibility to call commit() when you are done making changes and
        !            52: autocommit is turned off.
        !            53: 
        !            54: vim:tw=78:et
        !            55: 
        !            56: