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Tables. ESRM 250/CFR 520 Autumn 2009 Phil Hurvitz. Overview. Using ArcMap tables Querying tables Table relationships Graphs from tables. Using ArcMap tables: Introduction. Tables are just as important as coordinate (map) data Tables are used to hold attribute data - PowerPoint PPT Presentation
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
ESRM 250/CFR 520Autumn 2009Phil Hurvitz
Tables
1 of 42
ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Using ArcMap tablesQuerying tablesTable relationshipsGraphs from tables
Overview
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Tables are just as important as coordinate (map) data
Tables are used to hold attribute data Tables can be used to hold data that are
not explicitly spatial in nature Tables are the source of all basic statistics
Using ArcMap tables: Introduction
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Creating tables from existing sources Creating a new tableAdding fields (columns) to tablesAdding records (rows) to tables Editing values in table recordsCalculating fields
Using ArcMap tables: Overview
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Tables can be created from existing sources:
dBase files ASCII files
(tab or comma delimited) INFO files ODBC
connections
Creating tables from existing sources
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Tabular data can be obtained from ODBCdatabases (e.g., Oracle, Access)
Creating tables from ODBC connections
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
New (dBase, GDB) tables can be created from scratch
Creates a new file on disk New table is empty
Creating a new table
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Each field must be defined at add timeData type and storage parameters
need to be defined
Adding fields to tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Field data types should match the data they will store
Short Integer: Whole numbers from -32,768 to 32,768
Long Integer: Whole numbers from -2,140,000,000 2,140,000,000
Float: single-precision floating-point numbers with an accuracy to 6 places past the decimal
Double: double-precision floating-point numbers with an accuracy to 15 places past the decimal
Date: January 1, 0100 to December 31, 9999 Text: 1 - 255 characters
Tips for defining fields
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Precision = number of digitsScale = digits to the right of the
decimal point
e.g., 100.27
precision = 5scale = 2
Tips for defining fields
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Records can be added ad hoc to stand-alone tables
Do not add records to feature data (point, line, polygon) tables
Adding features (feature editing) will automatically add a record to the feature attribute table
Adding records to feature attribute tables will result in “phantom” records that are not associated with shape features
Adding records to tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Records can be added ad hoc to stand-alone tables
New records will have null values for all fields until updates are made
Adding records to tables
new record
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Values in a new field can be generated based on calculated expressions
Expressions can use other fields
Acts on selected set of records
Calculating fields
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Using ArcMap tablesQuerying tablesTable relationshipsGraphs from tables
Overview
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Making queriesSorting recordsDisplaying selected setsModifying selected setsBasic descriptive statisticsTable summaries
Querying tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Select records from tables “Select by attributes” Graphical interface to
table data Selected records in cyan
Making queries
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Displaying selected records will show only those records that are in the selected set
Displaying selections
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Record can be sorted ascending or descending by field
Sorting records
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Selecting records from feature tables also selects features from layers (and vice versa)
Displaying selected sets
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Existing selections can be broadened or narrowed
Additional query criteria Add to selection Remove from selection Further narrow down
current selection
Modifying selected sets
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Basic descriptive statistics can be generated for a field
will describe selected set (or all records if there is no active selection)
Basic descriptive statistics
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Summarizing tables Creates a new table Summarizes values in numeric fields by
values in a categorical field One output record per unique value in the
(categorical) field of interest Different summary statistics available
Table summaries
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Table summaries
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Using ArcMap tablesQuerying tablesTable relationshipsGraphs from tables
Overview
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
One-to-one relationship every record in Table A has a matching
value in Table B
Record relationships among tables
Table B
Table A
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Many-to-one relationship Many records in Table A have a match with
only 1 record in Table B
Record relationships among tables
Table B
Table A
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
One-to-many relationship Only 1 record in Table B has a match with
many records in Table B
Record relationships among tables
Table B
Table A
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Creates a virtual join (does not alter data sources)
Used for: one-to-one many-to-one
Joining tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Does not join, but allows simultaneous selections
Used for: one-to-one many-to-one one-to-many
Relating tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
“Relate” updates the selection on the related table based on field relationships
Relating tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Using ArcMap tablesQuerying tablesTable relationshipsGraphs from tables
Overview
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
What are graphs?Creating graphs from tablesGraph elementsGraph typesGraph legendsAxis propertiesAxis increments and grid linesDisplaying multiple fields
Making graphs from tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Graphical representation of tabular data
What are graphs?
numbers can bedifficult to interpret
graphs are easier to interpret
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Graphs are dynamically linked to tables
A selection on the table will be reflected in the graph
What are graphs?
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Creating graphs from tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Creating graphs from tables
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Graph elements
Graphs havemanyelementsto format
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
A number of different types and subtypes of graphs exist
Graph types
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
X and Y axes have various properties
Axis properties
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Increments and grid lines can be formatted in different ways
Axis increments and grid lines
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
A maximum value can be specified Be careful, the graph no longer shows the
data range
Axis increments and grid lines
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ESRM 250 & CFR 520: Introduction to GIS
© Phil Hurvitz, 1999-2009
Multiple fields can be displayed in the graph
Comparison of variables
Displaying multiple fields
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