GIS Unit 4

What does a DBMS contain?

Data model, data definition language, data dictionary, data-entry module, data update module, report generator, query language

What do relational database management systems (RDMS) consist of?

Data tables: rows define cases, object instances; columns define the known properties or attributes; tables can be linked through common keys

Features of ESRI Geodatabases

1. Build on an extended RDBMS: scalable (small to large databases), transactional model (edits will not be final until they are saved) 2. Built on the simple feature model: the ISO (International Standard Organization)/OGC (Open Geospatial Consortium) standard = open access, core geographic types and function to be used in a DBMS and accessed using the SQL

Steps to create a geodatabase

1. Create a new geodatabase 2. Create a new feature dataset. Assign coordinate system information. All data inside of the dataset must have the same coordinate system information 3. Add a new feature class. Create a new class. Import data: shapefiles, raster, images, etc

What are the types of geodatabases?

1. File geodatabase: recommended format for individual users, single user editing, platform-free, stores datasets in a folder of files on your computer, up to 1TB per dataset 2. Personal geodatabase: single user editing, windows only, stores data in Microsoft Access (.mdb), up to 2GB per dataset 3. Enterprise: multiuser databases - ArcSDE running on enterprise DBMSs

Name two types of table join

1. One-to-one (1:1) 2. Many-to-one (M:1), there is no one-to-many join option because it is not easily done with spatial data

Geodatabase data management

1. Use ArcCatalog 2. Import and convert data from other formats (Shapefiles, coverage, CAD, Raster) 3. Data model/scheme can be shared 4. What's inside? Tables, feature classes, raster dataset, feature datasets, annotation, dimensions, tools/models/scripts, rules, domains/subtypes/relationship classes, etc

What is the purpose of table join?

A way to associated records in one table with records in another table through a common field, known as a key.

What is a geodatabase?

A container to hold databases such as vector, raster, etc.

What is a mosaic data set?

A method of raster data organization, a collection of individual raster datasets (images) stored as a catalog and viewed as a mosaicked image. These can have different projections, resolutions, pixel depths and number of bands (doesn't have to be seamless). Provides advanced query and geoprocessing ability. Often recommended over "raster catalog"

What is a raster catalog?

A method of raster data organization, a collection of raster datasets defined in a table format in which each record represents an individual raster dataset in the catalog. Cannot be used with geoprocessing analysis tools. Typically used to display adjacent, fully overlapping or partially overlapping raster datasets without having to mosaic them into one large image

What is a spatial join?

A type of table join operation in which fields from one layer's attribute table are appended to another layer's attribute table based on the relative locations of the features in the two layers. Good way to find: the closest feature to another feature, what's inside a feature, what intersects a feature, how many points fall inside each polygon

What is a feature class?

Class, object-oriented DBMS terminology. A collection of objects (or features, records, cases, instance) with shared properties and behavior

What is a feature dataset?

Collections of feature classes that share the same coordinate system and have features that fall within a common geographic extent. Have associated information: spatial integrity, behavior (domains), relationship classes, topology (rules)

What is a database management system?

Databases can be physically stored in files or using special software programs, called DBMS. Advantage of DBMS over file-base datasets (ex. Shapefiles). Reduction of redundancy, easier maintenance and better security, multi-user access capability

What can be done in the fields tab in attribute tables?

Define which fields are displayed, define alias, format (currency, # of decimal places, etc)

What are object database management systems (ODMS)?

Designed to address the weaknesses of RDMS - deal with rich data types, geographic objects, sound and video

How is a feature dataset stored/used?

Feature classes can be stored directly under the database, or within feature datasets. Feature dataset use is preferable: easy to manage thematically related feature classes, all share the same spatial reference, topology can be defined and enforced within a dataset

How can attribute tables be stored?

Geodatabase, dBase (.dbf), INFO table (coverage), Microsoft Access/Excel, Text (tab or comma delineated)

Two methods of raster data organization

Mosaic Raster catalog

What are Object-Relational Database Management Systems?

ODBMS capabilites built on RDMS, which can be extended with spatial database extentions. (e.g. IBM DB2 (Spatial Extender), Informix Dynamic Server (Spatial Datablade), Microsoft SQL Server, Oracle DBMS (Oracle Spatial), PostgreSQL (PostGIS)

What is an object-oriented data model?

Object: an object is the basic atomic unit in an object data model and comprises all the properties that define the state of an object, together with the methods that define its behavior Class: a collection of objects of the same type, with individual objects in the class referred to as instances

What is normalization?

Process of reducing redundancy of database tables by splitting them into sub-tables that are rejoined at query time. Not just good for redundancy reduction bu also helps editing (e.g. if a manager changes, repeated cases need to be changed each time)

What is SQL? Its purpose?

Structured (or standard) Query Lanuage. Adopted by virtually all databases, designed to retrieve sets (rows and columns) of data from tables. Once tables are normalized and relationship are defined (i.e. common keys and how tables are connected), data in tables can be retrieved in a more flexible manner

Define ESRI Geodatabases

The geodatabase is the native data structure for ArcGIS and is the primary data format used for editing and data management. While ArcIS works with geographic information in numerous geographic information (GIS) file formats, it is designed to work with and leverage the capabilities of the geodatabase