Working with Tables Class 10 GISG 110

Objectives Working with Tables Table structure Table creation and manipulation Tabular formats Connecting tables and relationships Working with graphs and reports

Importance of tables Tables Are just as important as coordinate data in GIS Used to hold attribute data, and attributes control the what in GIS Can be used to hold data that are not explicitly spatial in nature –Related data –e.g., types of trees Are the source of all statistics, summaries, classifications, legends and graphs in GIS

Importance of tables Tables Have their own GUI, and their own set of operations In ArcMap, they can come from a variety of sources Multiple tables can be linked or joined based on common field values

Table basics Descriptive information about features Each feature class has an associated table One row for each geographic feature Right-click

Table anatomy Basic table properties Records/rows and fields/columns Column types can store numbers, text, dates Unique column names Records Fields (unique names) Attribute values

And then there was table Tables can be created… From existing sources From scratch or as a new table –Adding fields to tables –Adding records to tables –Editing values in table records

Creating tables from existing sources Tables can be created from dBase files (.dbf) ASCII files (tab or comma delimited) INFO files (.pat,.aat,.nat) Database connections

Creating a new table New dBase tables can be created from scratch In ArcCatalog, right-click on folder, select New, dBase Table, name table Creates an empty table

Tabular data field types Before adding data to our fields… Different field types store different kinds of values Choose the right field type for the right value Field types vary according to table format TextDateShortLongBLOBFloat Jupiter7/16/ Name: Jupiter Moons: 16 Diameter: 142,984 km Date of Comet Shoemaker-Levy Impact: 7/16/1994 Rotation period 9.8 hr

Adding fields to tables Each field must be defined at a time In ArcCatalog (Preview tab), select Options, Add Field

Manipulating tables Once table is populated or existing table is opened in ArcMap or ArcCatalog –Sort ascending or descending –Summarize –Calculate Values –Statistics –Freeze/Unfreeze Column Right-click

Sorting records Right-click on field Sort Ascending or Descending In ascending order now

Displaying selected records Selected records from tables also select features from themes

Freezing/Unfreezing Fixes a column in place for better viewing of the table's contents A frozen column stays in place while the other columns scroll normally

Summarizing tables Creates a new table Summarizes values in numeric fields Different summary statistics available

Calculating values Acts on selected set of records Record values can be altered based on expressions Expressions can use other fields

Basic descriptive statistics Can be generated for a field Describes selected set (or all records if there is no active selection)

ArcGIS tabular formats Each ArcGIS spatial format has a native tabular format –Coverage: INFO –Shapefile: dbf –Geodatabase: RDBMS Create a link between related tables Some spatial formats can link with multiple tabular formats ArcGIS can convert between formats

Connecting tables Attributes can be stored in feature table or separate table Connect tables with common key values (fields) Must know table relationships (cardinality) Common fields

Table relationships How many A objects are related to B objects? Types of cardinality –One to one, one to many, many to one, or many to many Must know cardinality before connecting links –Prevents potential omission errors

One-to-one relationship Every record in Table A has a matching value in Table B

Many-to-one relationship Many records in Table A have a match with only one record in Table B

One-to-many relationship Only one record in Table B has a match with many records in Table A Building occupancy –One building (Table B) –Many tenants (Table A) –The join is to Table B

Joins and relates Two methods to associate tables in ArcMap based on a common field Join appends the attributes from one onto the other –Label or symbolize features using joined attributes Relate defines a relationship between two tables

Connecting tables with joins Physical connection between two tables –Creates a virtual join –Does not alter data sources Appends the attributes of two tables Assumes one-to-one or many-to-one cardinality Access from layer properties

Joining external table to a feature class Table has to be added into ArcMap Table should be filtered in Excel program Common field must exist between feature class and table Columns cells must have same format between table and feature class

Connecting tables with relates Define relationship between two tables Tables remain independent –Does not join but allows simultaneous selections Additional cardinality choices –One to many, many to many

Relating tables Unlike joining tables, relating tables simply defines a relationship between two tables The associated data isnt appended to the layers attribute table like it is with a join Instead, you can access the related data when you work with the layers attributes – –For example, if you select a building, you can find all the tenants that occupy that building – –Similarly, if you select a tenant, you can find what building it resides in

More about tables… Working with tables – with_tables.pdf with_tables.pdfhttp:// with_tables.pdf

Graphs and Reports

Graphs Summarize tabular information Variety of graph formats Set display properties Add to a map in Layout view

Graphs Graphical representation of tabular data Numbers are difficult to interpret Graphs are easy to interpret

Graphs Dynamically linked to tables

Graph display properties For data features (Data view) Accessed through layer Properties Symbology Charts Pie, Bar/Column, Stacked

Graph formats A number of types of graphs exist for the layout view

Add to map in layout view Top 25 International Airports Proximity to Point of Sales with Population and Drive Times

Reports Organize and display tabular data Group and format data Save and export Two reporting tools –ArcMap Report writer –Crystal reports

ArcMap Report Writer Quick, easy, professional report creation Add images Choose fields and records Add borders Title Date and page numbers Calculate summary statistics

Crystal reports A more powerful reporting tool Export to Crystal Reports format Wizard aids report creation Distributed with ArcMap –To access reporting tools, must have Crystal reports installed on your machine

Review 1. There are different field types for different table formats. (T/F) 2. Each field should have a unique name. (T/F) 3. Different field types store different kinds of values. (T/F) 4. Attributes and features are linked by ______. 5. Coverages store attributes in an _______ file, shapefiles store attributes in a _______ file, and geodatabase store attributes in a _____. 6. What is table cardinality and why is it important? 7. What is the difference between a join and relate? 8. Multiple tables can be joined based on common field values. (T/F) 9. Attributes can be stored in feature tables only. (T/F) 10. What are the four steps to joining an external table to a feature class?

Remainder of Class Break GISG 110 Survey – =721MlLPpDXLXsuzkJ2FVhg_3d_3d =721MlLPpDXLXsuzkJ2FVhg_3d_3dhttp:// =721MlLPpDXLXsuzkJ2FVhg_3d_3d ESRI Chapter 9 Joining and relating tables Exercise 3 questions and SANDAG exercise