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

       Dave Rolsky, <autarch@urth.org>

perl v5.34.0                                       2022-06-14                    Alzabo::Create::ForeignKey(3pm)

       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_relation method method, and it will create the necessary intermediate linking
       table for you.

       "Alzabo::ForeignKey"

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

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

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

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

   set_cardinality(\@cardinality)seeabovefordetails
       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.

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

         use Alzabo::Create::ForeignKey;