Tony Nixon
Database Project Paper
February 15, 2013
Zoning Database Design Project
This database design project involves the creation of a database schema to successfully
portray a municipal GIS zoning layer and supporting tabular data that can be implemented by
various organizations for editing and viewing purposes. The project takes place in Auburn,
Alabama. A needs assessment was performed with the planning director from the Planning
Department on essential tabular and field information that must be incorporated based on the
organizations that require access to the database. An appendix is provided showing the overall
schema which includes all tables, fields, domains, subtypes, and relationship classes. A use case
diagram is also included to portray the roles of the various organizations.
The foundation of this database comes from the parcel and zoning layers. All tabular
information are linked to these polygon layers through relationship classes. The parcel layer
(Parcel_Layer) accurately represents all the parcels of Auburn, Alabama. Each parcel has one
land owner and address, and can be uniquely identified by its fourteen-digit parcel number. The
parcel number is consisted of a township, range, section, and its individually unique number. The
phone number of the owner is also provided in each parcel.
The zoning layer (Zoning_Layer) is derived from the parcel layer. There is one or more
zoning polygons in each parcel. Each zone is represented by its unique five-digit identifier and
the parcel number of the parcel it resides in. Each zone polygon has a specific zone code and
zone use that is permitted by the planning department. To maintain data integrity in the database,
the zone code field is a subtype for the zoning layer field class. There are also six separate coded
domains for the six subtype values that signify the zone uses permitted in each zone code. The
most current book and page is also displayed with each zone polygon. Since the parcel and
zoning layers coincide, there is a relationship class (ParcelHasZones) relating the two attribute
tables.
A major concern for the Planning Department is to keep track and limit any zoning
violations that are being committed by land owners. Zoning violations often involve activities
that affect the safety, health, or quality of life on both the zone polygon and any adjacent zones.
A table (Zoning_Violations) is created to access any violations committed per zone for the
Planning Department and the ability to manage inspections. The Planning Department has four
planners (inspectors) inspecting the zones for the zoning violations. For data integrity purposes, a
coded domain is created for the inspector field. An inspection date is also included in the table,
so new inspections can be readily scheduled when necessary. By providing the parcel and zone
identification numbers for each violation, a relationship class (ParcelHasViolations) is created
between the violations table and the parcel layer, so violations can easily be associated with each
parcel on the map.
Zoning changes can be requested at any time by the land owner if they feel that the
current zone code and zone use is inconsistent with the use they prefer. In order to be granted a
zoning change, owners must submit a Zoning Change Request Form. Each form includes a
request number as a unique form identifier. Forms require accurate owner information as well as
the parcel and zone the change is being requested. The original zone code and use will be
recorded along with the requested zone code and use. Owners must also supply sufficient
reasoning for the zone change. The other portion of the request form is left for the decision of the
Planning Department. A planner is to inspect the zone and make a decision based on the
condition of the zone and any violations that are on record. A board date is then scheduled based
on any decisions of the planner for the finalization of the zone change. The form will be
submitted and recorded by the Clerk and Recorder, and entered into a table
(Zoning_Form_Request_Change) in the database. There are coded domains for the planner, the
requested and original zone codes and uses, and the planner’s decision to maintain data integrity.
The Planning Department keeps a book and page as a log of every zoning change and
other zoning requests that have been made in the city of Auburn. Zoning changes that have been
declined by the Planning Department are not recorded in the book and page. Each page in a book
represents one zone change that occurred in a parcel. A table (Book_Page) is made to easily
search through the book and page for certain zoning change information. It provides essential
information such as the zone polygon and its owner. The request number from the request form
that was submitted for the zone change is also included. There are two significant dates in the
table for each book and page. The board date in which the zone change was decided, and the
latest date in which the book and page was updated per zone polygon. With the latest date
provided in the table, the Planning Department will know which book and pages have not been
recorded by referencing recent request forms. Therefore, there is a relationship class
(RequestHasPage) between the request forms and the book and page. There is also a relationship
class (ZoneHasPages) between the zoning layer and the book and page for the ability to show the
complete log of zoning changes that have occurred in each zone.
The final aspect of the database represents tax assessments associated with each zone. A
tax assessment is basically an estimate of what a piece of property is worth. Tax assessors make
the assessments on each zone based on the market value of the property. A table
(Tax_Assessments) is made to show each tax assessment per zone polygon. All relevant
information about the parcel and zone identification are included for each tax assessment. The
tax assessor along with the assessment date is also included in the table. There is a field for the
market value if relevant information about the zone is provided by the owner. If a market value
cannot be obtained, then the tax assessor has to make an estimated appraisal value. The overall
property tax is determined from one of these values and entered as the tax assessment. There is a
relationship class (ParcelHasAssessments) between the parcel layer and the tax assessments, so
assessments can easily be associated with each parcel on the map.
Appendix