Lecture Note
Database Management and Geodatabases
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University:
California State University, Northridge -
Course:
GEOG 306/L | Intermediate Geographical Information Science and Lab Academic year:
2008
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Views:
174
Pages:
18
Author:
Jadon Walton
Lecture 3a
Database Management
and
Geodatabases Lecture 3:
Outline
I.
Databases
A. Attribute Data
B. Types of Databases
A. Relational vs. Non-Relational
II. Table Relationships
A. Preparing Tables
B. Joins and Relates
III. Geodatabases
A. Types
B. Structure and Creation
C. Geodatabase Behavior
A. Schemas and Domains
B. Topology
D. Creating and Editing Data
E. Geodatabase Annotation Attribute Data
Use to capture non-spatial aspects of an entity.
Most often contained in a table
Attributes can be categorized as:
Nominal: Provide descriptive info. Ex. Color, names,
types of soil. No implied order, size of quantity.
Ordinal: Imply rank order or scale. Does not represent
differences in scale. Ex. Descriptive (short, medium,
long) or numeric (1-100).
Interval/Ratio: Where both order and absolute
differences in magnitude are represented. Ex. Length,
weight, height or depth. I. Database Components
DBMS (Database Management System): A specialized
computer program for organizing and manipulating data.
Note: A database is the organized collection of data, often created or manipulated with the
help of a DBMS. The terms Database and DBMS should not be used interchangeably. III. Non-Relational Databases
Flat Files IV. Relational Databases Preparing Tables for ArcGIS
1. In Excel:
Prepare your table.
Define the data ‘range’ by doing the following….
Select all the populated cells in the table
Go to Insert Æ Name Æ Define…
Type a name (i.e. ‘database’).
Save Excel file
2a. Excel 2003 (and older versions):
Click File ÆSave As… provide a name and choose the drop-down arrow next to
“Save As Type:”
Choose ‘DBF 4 (dBASE IV)’
2b. Excel 2007
In Excel 2007, save the table as, 'Excel 97-2003 Workbook' (.xls format).
Navigate to the .xls table location through ArcCatalog, and expand (double-click)
the file to view the worksheets.
Right-click on the worksheet representing the table. Select Export > To dBase
(single).
Using Excel Spreadsheets in ArcGIS: Fields
Field Types:
Make sure you consider the appropriate field type, size and properties in
advance. Ex. Text, integer, double…
Spaces and certain characters are not supported in field names.
Eliminate anything that is not alphanumeric or an underscore.
Limit number of characters
Features classes < 64 characters
.dbf files <10 characters
Field Creation:
Make sure you are not editing the data or accessing the data in any other
applications.
In ArcCatalog
Right-click on layer and select “Layer Properties”
In Arcmap
Stop editing, open the attribute table and go to Options Æ Add Field. V. Table Relationships
One-to-One Relationship
One-to-Many & Many-to-One
Relationship V. Joining and Relating Tables
Joining Tables: Appends the attributes from one table
onto another based on a field (key) common to both.
Relating Tables: Defines a relationship between two
tables - also based on a common field (key) - but doesn't
append the attributes of one table to the other. Instead,
you can access the related data when necessary. V. Joining and Relating Tables
Tables are linked through Keys.
Keys are items or fields that meet certain
requirements (data format and length) and
are used to index the records.
Note: Misspelling or spaces in key values
can create problems with your join or relate
process.
Ex. Northridge vs Nothridge or NewMexico vs
New Mexico. V. Joining and Relating Tables
To obtain info about a key
field, go to Layer Properties
and click on the Fields tab.
After joining a table, you
can preserve the join by
right-clicking on the
shapefile or feature class
and selecting Data…Export
Data. Geodatabases
The geodatabase is a container for storing spatial and
attribute data and the relationships that exist among
them
Format introduced by ESRI with ArcGIS® software
Primary format we will be working with in this class.
Icons identify
feature types Geodatabases and Data
Organization
Geodatabases can consist of:
Feature Datasets
Feature Classes
Annotation Feature Classes
Raster Datasets
Nonspatial Tables Types of Geodatabases
Scalable Functionality
3 Types:
File Geodatabases: Stored as folders in a file system. Each
dataset holds up to 1 TB of data. Fast performance, less
restrictive editing locks and supported by many platforms.
Personal Geodatabases: Stored within Microsoft Access. Holds
up to 2 GB of data.
ArcSDE Geodatabases: Stored in a relational database using
Oracle, Microsoft SQL Server, IBM DB2, or IBM Informix.
Requires the use of ArcSDE software. Unlimited in size and
numbers of users. Creating Geodatabases
In ArcCatalog:
Navigate to the folder you want to create the
GDB in.
Right click and select New…
Select either File or Personal Geodatabase.
Right-click on or in the GDB to create new
feature datasets, classes or tables. Geodatabase Behavior
Schemas
A schema defines the physical structure of the geodatabase along with the rules,
relationships, and properties of each dataset in the geodatabase.
Users often share their schemas with others.
Data model templates (schemas) exist for many GIS applications. For example,
ESRI publishes a series of ArcGIS data models for the user community. Geodatabase Behavior
Domains
A list or range of valid attributes for an attribute
that limits values. Helps to limit user error.
Range Domains
Ex. Pipe diameter (range = 1-5 feet)
Coded Value Domains
Ex. Vegetation Type (Tree, Scrub or Grass).
Database Management and Geodatabases
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