Alzabo::Create::ForeignKey(3pm) 			User Contributed Perl Documentation			   Alzabo::Create::ForeignKey(3pm)

NAME

       Alzabo::Create::ForeignKey - Foreign key objects for schema creation.

SYNOPSIS

	 use Alzabo::Create::ForeignKey;

DESCRIPTION

       A foreign key is an object defined by several properties.  It represents a relationship from a column or columns in one table to a column
       or columns in another table.

       This relationship is defined by its cardinality (one to one, one to many, or many to one) and its dependencies (whether or not table X is
       dependent on table Y, and vice versa).

       Many to many relationships are not allowed.  However, you may indicate such a relationship when using the Alzabo::Create::Schema->add_rela-
       tion method method, and it will create the necessary intermediate linking table for you.

INHERITS FROM

       "Alzabo::ForeignKey"

       Note: all relevant documentation from the superclass has been merged into this document.

METHODS

       new

       The constructor takes the following parameters:

       * columns_from => "Alzabo::Create::Column" object(s)
       * columns_to => "Alzabo::Create::Column" object(s)
	   These two parameters may be either a single column or a reference to an array columns.  The number of columns in the two parameters
	   must match.

       * cardinality => [1, 1], [1, 'n'], or ['n', 1]
       * from_is_dependent => $boolean
       * to_is_dependent => $boolean
       * comment => $comment
	   An optional comment.

       It returns a new "Alzabo::Create::ForeignKey" object.

       Throws: "Alzabo::Exception::Params"

       table_from

       table_to

       Returns the relevant "Alzabo::Create::Table" object.

       columns_from

       columns_to

       Returns the relevant "Alzabo::Create::Column" object(s) for the property as an array.

       column_pairs

       Returns an array of array references.  The references are to two column array of "Alzabo::Create::Column" objects.  These two columns cor-
       respond in the tables being linked together.

       set_columns_from ("Alzabo::Create::Column" object(s))

       Sets the column(s) that the relation is from.  This can be either a single column object or a reference to an array of column objects.

       Throws: "Alzabo::Exception::Params"

       set_columns_to ("Alzabo::Create::Column" object(s))

       Sets the column(s) that the relation is to.  This can be either a single column object or a reference to an array of column objects.

       Throws: "Alzabo::Exception::Params"

       cardinality

       Returns a two element array containing the two portions of the cardinality of the relationship.	Each portion will be either '1' or 'n'.

       from_is_dependent

       to_is_dependent

       Returns a boolean value indicating whether there is a dependency from one table to the other.

       is_one_to_one

       is_one_to_many

       is_many_to_one

       Returns a boolean value indicating what kind of relationship the object represents.

       set_cardinality (@cardinality) see above for details

       Sets the cardinality of the foreign key.

       Throws: "Alzabo::Exception::Params"

       set_from_is_dependent ($boolean)

       Indicates whether or not the first table in the foreign key is dependent on the other (i.e. whether the 'from' table is dependent on the
       'to' table).

       set_to_is_dependent ($boolean)

       Indicates whether or not the second table in the foreign key is dependent on the other (i.e. whether the 'to' table is dependent on the
       'from' table).

       id

       Returns a string uniquely identifying the foreign key.

       is_same_relationship_as ($fk)

       Given a foreign key object, this returns true if the two objects represent the same relationship.  However, the two objects may represent
       the same relationship from different table's points of view.

       comment

       Returns the comment associated with the foreign key object, if any.

       set_comment ($comment)

       Sets the comment for the foreign key object.

AUTHOR

       Dave Rolsky, <autarch@urth.org>

perl v5.8.8							    2007-12-23					   Alzabo::Create::ForeignKey(3pm)