Arc GIS Arc Map Tables Agenda Opening tables

Arc. GIS: Arc. Map Tables

Agenda • • • Opening tables The interface Working with columns Working with records Making selections Advanced table tools ▫ Add fields ▫ Relates (links) ▫ Joins • Editing table content • Editing table structure

Opening tables • Types of tables ▫ Layer Attribute Tables ▫ “Other” Tables – Not associated with a geometry file • Adding Tables to the Map ▫ Layer attribute tables are loaded by default when the layer is added ▫ Other tables can be added to the map using the Add Data button, similar to adding a spatial data source. ▫ When “other” tables are added to the map, they are available from the “Source” tab of the View Table of Contents • Opening tables ▫ Layer Attribute Tables can be opened by right-clicking on the layer in either the Source or Display tab of the Arc. Map Table of Contents and selecting Open Attribute table ▫ Other tables may be opened by right clicking on them in the Source tab of the Arc. Map Table of Contents and selecting Open.

The table interface records fields First record Next record Previous record Last record Current record Number of records

Working with columns • Select columns ▫ Click on a column header to select it, this will highlight the column to indicate that it has been selected. ▫ Select multiple columns by holding down the control key and clicking on additional column headers • Changing column width ▫ Click on the line between two columns to the right of the name of the column that you wish to resize. Drag right to enlarge, left to shrink ▫ A black line indicates where the new column edge will be located • Rearranging columns ▫ Click on the column heading and drag it to the desired position. A red line should show where the column will be placed. • Freezing columns ▫ Locks a column in the leftmost position on the table, allowing you to view that column while scrolling others past it. ▫ Right-click on the column header and select “Freeze/Unfreeze Column” to freeze it. ▫ A thick black line on the columns right side indicates that it has been frozen.

Working with records Enter a record number Move Back • Navigating Move to beginning Move to end Move forward ▫ Navigation info available at the bottom left of the table window ▫ Move to beginning move back, forward, to the end, or enter a specific record number • Find records ▫ From the options menu select Find & Replace ▫ You can specify Match Type, Search Order, and field(s) you wish to search • Sort records ▫ Right click on the header field you wish to sort on and select an ascending or descending sort

Making Selections • Select Records Interactively ▫ Click on the gray box to the left of the record you wish to select. Selection is indicated with highlighting ▫ Click and drag to select several adjacent records, use control + click to select multiple non-adjacent records • Select by Attributes ▫ Choose Options>Select by Attributes to open the select by attributes dialog ▫ Choose a selection method at the top of the dialog ▫ You may either use the menus and buttons to help build a query statement, or enter one directly if you are familiar with the syntax • Other Selection Tools ▫ Within the options menu there also tools to: select all, switch selection, clear selection.

Advanced table tools • • Field statistics Adding fields Relates Joins

Add field • • Right-click on Table Options>Add Field… Define Name, Type, and field properties Data Types: Field Properties

Calculate Geometry • Area (polygon) • Perimeter (polygon) • X/Y Coordinate of Centriod (polygon/point) • Length (line) • X/Y Coordinate of line start/end (line)

Field Calculator • Use the Field Calculator to add data to fields and perform text or numerical operations

Add Field (exercise 1)

Joins and Relates • Sometimes it is necessary to relate data between two tables. For example, perhaps you have a table containing information about census tract which you would like to connect to a census tract attribute table. There are two tools which can be used for this task depending on the type of relationship you are seeking, and the structure of the tables you are using. • Joins ▫ Joins are the most functional type of relationship because they simply append data to the right of the attribute table, expanding the content of the table. Once data has been joined to an attribute table, the joined data can be used for analysis and Symbology. • Relates ▫ Not as powerful as joins, relates can be used to define “One-to-Many” and “Many-to-Many” relationships. Relates are mainly used as another method of performing queries.

Joins/Relates Many to One to Many

Join Tables - Creating • Joins are similar to relates, but in addition to defining a relationship between two tables, a join actually visually combines the tables based on that relationship. In order for the output table to be accurate, you should only use joins with one-to-one or many-to-one relationships • Create a join by right clicking on a layer in the Table of Contents and selecting Joins and Relates>Join… • The procedure for joining tables is almost identical to that for creating relates. The dialog for creating joins is slightly different.

Join Table - using • As a result of a join, the table which is joined to will gain all of the fields of the table which is joined to it. To minimize confusion, the fields that have been joined will have the name of the source table prepended to the original column names. In the example below, the table tract_pop has been joined to the layer attribute table of tracts • Joins do not affect the data source, they only exist with the Map Document. If you need a single file which looks like the output of the join, you should use the export the table (available in the options menu). This will create a new table which contains both the original and joined fields.

Relate tables - creating • If you need to create a one-to-many or many-tomany relationship between two tables, you can create a “Relate”. Basically you are just defining the relationship between the tables • Create a relate by right clicking on a layer in the Table of Contents and selecting Joins and Relates>Relate… • In the relate dialog you must indicate which field contains the common attribute between the two tables, as well as the table that you wish to relate to. You can also indicate a name for the relate

Relate tables – accessing (exercise 2) • Once a relate is created, you only have to access it when needed. Select a desired set of records from one table. To see the corresponding records in the related table, click Options>Relate Tables>Relationship name This will open the related table with all corresponding records highlighted. • To remove a relate, right click on the layer in the Table of Contents and select joins and relates>remove relates> relationship name