===== Database Table Description of "filter" =====

=== Name ===

filter

=== Description ===

=== Purpose ===

=== Schema ===

<code sql>
create table filter (
  identifier            integer not null primary key,
  type                  integer not null references filter_type(identifier),
  users                 integer not null references users(identifier),
  date_of_purchase      timestamp,
  purchased_new         char(1) check (purchased_new in ('t', 'f')),
  access_rights         integer not null references access_type(identifier),
  serial_number         varchar(20);
);
</code>

=== References tables ===

  * access_rights references [[access_type sql table|access_type]](identifier)
  * type references [[filter_type sql table|filter_type]](identifier)
  * users references [[users sql table|users]](identifier)

=== Is referenced by tables ===

  * [[photo_tech sql table|photo_tech]](filter) references identifier

=== Related sequences ===

  * [[filter_id_sequence sql sequence|filter_id_sequence]]

=== Related indexes ===

  * [[filter_type_idx sql index|filter_type_idx]]
  * [[filter_users_idx sql index|filter_users_idx]]

=== Related functions ===

  * [[number_of_filter_references sql function|number_of_filter_references]]

=== Related views ===

  * [[view_filter sql view|view_filter]]

=== History ===

== Used first ==

Version 2.5

== Used last ==

Still in use

== Schema change history ==

= Version 2.5 =

<code sql>
create table filter (
  identifier            integer not null primary key,
  type                  integer not null references filter_type(identifier),
  users                 integer not null references users(identifier),
  date_of_purchase      timestamp,
  purchased_new         char(1) check (purchased_new in ('t', 'f')),
  access_rights         integer not null references access_type(identifier)
);
</code>

= Version 2.33 =

<code sql>
-- Add another column to the filters
alter table filter add serial_number varchar(20);
</code>

== Data change history ==