]project-open[ Data-Model “Categories”

]po[ “Categories” The ]project-open[ Data-Model , Frank Bergmann, 2010-09-22 This tutorial explains the purpose and use of “categories” in ]project-open[. Categories are the most widely used data-structure in the system. They are used to represent the status and type of business objects and as general classifiers. In other words: Categories represent the values of most GUI drop-down boxes in the system.

GUI Example ,[object Object],[object Object],(The list of Project States from http://demo.project-open.net / )

Problems Solved by “Categories” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],(The list of Project States from http://demo.project-open.net / )

Solution: "Categories" ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],object_type_id object_status_id object s object_type_id name object_type s description name description ... object_type_id object_status_id object s name description ... category_id name im_categories description category_type ] po [ DB-Design: All type and status information is stored in a single "im_categories" table. The "Classical" DB-Design: Every table has it's own tables for type, status and similar information. object_status_id name object_stat e s description

Hierarchical Categories ,[object Object],[object Object],Potential “ Top” Open Closed Inquiring Qualifying Declined Delivered Quoting Quote Out Invoiced Deleted Canceled (The list of Project States from http://demo.project-open.net / ) Every arrow corresponds to one entry in the im_category_hierarchy table

Categories Shortcut Functions ,[object Object],[object Object],[object Object],SELECT im_category_from_id( 71 ) ; im_category_from_id --------------------- Potential (1 row) select * from im_sub_categories(57); im_sub_categories ------------------- 54 55 57 10244 10245 select im_category_new( nextval('im_categories_seq')::integer, 'Test', 'Intranet Project Status‘ ); im_category_new ----------------- 0

Categories as Constants ,[object Object],[object Object],[object Object],[object Object],[object Object],„ All“ Open Inquiring Qualifying Quoting Quote Out Declined Delivered Invoiced Constants, don't change! Freely Configurable Deleted Canceled Closed Potential

Categories SQL Examples “Cookbook” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Categories Definition -- We use categories as a universal storage for business -- object states and types, instead of a zillion of tables -- like 'im_project_status' and 'im_project_type'. create sequence im_categories_seq start 100000; create table im_categories ( category_id integer constraint im_categories_pk primary key, category varchar(50) not null, category_description varchar(4000), category_type varchar(50), category_gif varchar(100) default 'category', enabled_p char(1) default 't' constraint im_enabled_p_ck check(enabled_p in ('t','f')), -- used to indicate "abstract" -- super-categorys that are not -- valid values for objects. -- For example: "Translation -- Project" is not a project_type, -- but a class of project_types. parent_only_p char(1) default 'f' constraint im_parent_only_p_ck check(parent_only_p in ('t','f')) ); Category Hierarchy -- Optional system to put categories in a hierarchy. -- This table stores the "transitive closure" of the -- is-a relationship between categories in a kind of matrix. -- Let's asume: B isa A and C isa B. So we'll store -- the tupels (C,A), (C,B) and (B,A). -- This structure is a very fast structure for asking: -- -- "is category A a subcategory of B?" -- -- but requires n^2 storage space in the worst case and -- it's a mess retracting settings from the hierarchy. -- We won't have very deep hierarchies, so storage complexity -- is not going to be a problem. create table im_category_hierarchy ( parent_id integer constraint im_parent_category_fk references im_categories, child_id integer constraint im_child_category_fk references im_categories, constraint category_hierarchy_un unique (parent_id, child_id) ); Extract Categories Without Join -- A helper functions to make our queries easier to read create or replace function im_category_from_id (integer) returns varchar as ' DECLARE p_category_id alias for $1; v_category varchar(50); BEGIN select category into v_category from im_categories where category_id = p_category_id; return v_category; end;' language 'plpgsql'; -- Example: -- select im_category_from_id(48); Create a New Category Entry insert into im_categories ( category_id, category, category_type, category_description, enabled_p, aux_int1, aux_int2, aux_string1, aux_string2 ) values ( :category_id, :category, :category_type, :category_description, :enabled_p, :aux_int1, :aux_int2, :aux_string1, :aux_string2 );

Frank Bergmann [email_address] www.project-open.com

]project-open[ Data-Model “Categories”

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]project-open[ Data-Model “Categories”