Tangram::Relational(3pm)				User Contributed Perl Documentation				  Tangram::Relational(3pm)

NAME

       Tangram::Relational - Orthogonal Object Persistence in Relational Databases

SYNOPSIS

	  use Tangram;

	  $schema = Tangram::Relational->schema( $hashref );

	  Tangram::Relational->deploy($schema, $dbh);

	  $storage = Tangram::Relational->connect( $schema,
	     $data_source, $username, $password );

	  $storage->disconnect();

	  Tangram::Relational->retreat($schema, $dbh);

DESCRIPTION

       This is the entry point in the vanilla object-relational persistence backend. Vendor-specific backends should be used when they exist. Cur-
       rently Mysql, Sybase and Oracle have such backends; see Tangram::mysql, Tangram::Sybase and Tangram::Oracle.

       More backends could be added in the future; they might implement persistence in XML documents, pure object databases, using C database
       libraries to bypass the need for an RDBMS, etc.

CLASS METHODS

       schema

	  $schema = Tangram::Relational->schema( $hashref );

       Returns a new Schema object. See Tangram::Schema.

       deploy

	  Tangram::Relational->deploy($schema);
	  Tangram::Relational->deploy($schema, HANDLE);
	  Tangram::Relational->deploy($schema, @dbi_args);

       Writes SQL statements for preparing a database for use with the given $schema.

       Called with a single argument, writes SQL statements to STDOUT.

       Called with two arguments, writes SQL statements to HANDLE. HANDLE may be a DBI connection handle or a file handle.

       Called with more than two arguments, passes all but the first to DBI::connect() and writes statements to the resulting DBI handle, which is
       automatically closed.

       The SQL code is only guaranteed to work on newly created databases.

       connect

	  $storage = Tangram::Relational->connect( $schema,
	     $data_source, $user, $password, \%options )

       Connects to a storage and return a handle object. Dies in case of failure.

       $schema is a Schema object describing the system of classes stored in the database.

       $data_source, $user and $password are passed directly to DBI::connect().

       \%options is a reference to a hash containing connection options. See Tangram::Storage for a description of available options.

       retreat

	  Tangram::Relational->retreat($schema);
	  Tangram::Relational->retreat($schema, HANDLE);
	  Tangram::Relational->retreat($schema, @dbi_args);

       Remove the tables created by deploy(). Only guaranteed to work against a database that was deployed using exactly the same schema.

       For an explanation of the possible argument lists, see deploy.

WRITING A VENDOR DRIVER

       Like Charles Moore (inventor of Forth) used to say, "standards are great, everybody should have one!".

       Tangram can take advantage of extensions available in some SQL dialects.

       To create a vendor-specific driver, call it "Tangram::Foo" (where "Foo" is the name of the DBI driver, as would be selected with the DBI
       connection string "dbi:Foo:"), and derive "Tangram::Relational".

       For now, the existing back-ends should be used as examples of how to extend Tangram to support different databases or utilise some of their
       more exotic features.

perl v5.8.8							    2006-03-29						  Tangram::Relational(3pm)