NAME

SQL::Schema::Sequence - An Oracle sequence

SYNOPSIS

  my $sequence = SQL::Schema::Sequence->new(%attr);

  my $sql = $sequence->create_statement;
  print $sql;

  print "$sequence";

DESCRIPTION

SQL::Schema::Sequence is a class for objects representing an Oracle sequence. The methods of an instanciated object do allow to access the information within a database's data dictionary and to represent them as SQL create statements and the like using the proper SQL dialect.

Constructors

  $sequence = SQL::Schema::Sequence->new(%attr);

The new method instanciates a sequence object. The object is an in memory representation of a (possible) oracle sequence. The attributes are given as key value pairs by the hash %attr. Possible keys are:

  key            required?   value description

  schema_name    no          The name of the schema for

  sequence_name  yes         The name of the sequence (without a
                             preceeding schema name).

  min_value      no          number
  max_value      no          number
  increment_by   yes         number
  cycle_flag     no          either `Y' or `N'; default: `N'
  order_flag     no          either `Y' or `N'; default: `N'
  cache_size     yes         number
  start_with     yes         number

These keys (except schema_name and start_with) and their possible values correspond exactly to the data dictionary view user_sequences and are described within Oracle's Server Reference.

The value for start_with is the number the sequence should start with.

  $sequence = SQL::Schema::Sequence->select($dbh,$name);
  $sequence = SQL::Schema::Sequence->select($dbh,$name,$schema_name);

The select method fetches the attributes required by new from the database and returns the sequence object. (It calls new internally.) It takes the following arguments:

If the sequence with the name $name could not be found within the database, the method returns undef.

The method's arguments are as follows:

$dbh

A database handle as defined by DBI(3).

$name

The name of the sequence without preceeding schema name.

$schema_name

Optionally the name of the database schema.

Warning: The method introduces a bug. The value for start_with required by the new method is selecte as last_number + increment_by. If the resulting value is outside the inverval given by min_value and max_value this is not checked. This means: In extreme cases it might happen, that the statement produced by the create_statement method can not really be executed on by a database.

Methods

The following attribute methods do return the current value of the attributes (as handed over to the new method):

  $schema_name = $sequence->schema_name;
  $name = $sequence->name;
  $min_value = $sequence->min_value;
  $max_value = $sequence->max_value;
  $increment_by = $sequence->increment_by;
  $cycle_flages = $sequence->cycle_flags;
  $order_flags = $sequence->order_flags;
  $cache_size = $sequence->cache_size;
  $start_with = $sequence->start_with;

The return value of cycle_flag resp. order_flag is either Y or N. This is somewhat uncomfortable for perl programmers. You might want to use the following two methods instead:

  $cycle_flag = $sequence->cycle;
  $order_flag = $sequence->order;

They do return 1 resp. 0 where their corresponding attribute method returns Y resp. N.

  my $qname = $sequence->qualified_name;

Returns the qualified name of the sequence which is the concatenation of schema_name and sequence_name with a in between if schema_name has been set. Otherwise only sequence_name is returned.

  $sql = $sequence->create_statement;
  $sql = "$sequence";

Returns a string containing an SQL statements for creation of a sequence. This method is overloaded with the string operator. So the two examples above are equivalent.

  $sql = $sequence->drop_statement;

Returns a string containing an SQL statement that would drop this sequence.

BUGS

The select method introduces a bug. This occurs if the value selected from the database for start_with is not valid. For more information see warning at select.

AUTHOR AND COPYRIGHT

  SQL::Schema::Sequence is Copyright (C) 2000,
    Torsten Hentschel
    Windmuehlenweg 47
    44141 Dortmund
    Germany

    Email: todd@bayleys.ping.de

  All rights reserved.

  You may distribute this package under the terms of either the GNU
  General Public License or the Artistic License, as specified in the
  Perl README file.