Introduction to ArcGIS for Environmental Scientists Module 2 – Fundamentals Chapter 7 – Queries

7-1 Introduction to ArcGIS Explore different ways to query databases –Interactive –Attribute –Location (Spatial) –Graphic Tips and tricks to optimize viewing geospatial data –Bookmarks –Overview, magnify and viewer window –Options and Customizing ArcMap Chapter 7 - Objectives

7-2 Introduction to ArcGIS Use to select other features Export selected features to a separate file Create a new layer –Subset faster than including entire set Create a Report Use selected set for further analysis Why Use Selection?

7-3 Introduction to ArcGIS Selection Layers All vector layers are selectable by default when added to the map Layer selectabillty is managed through the List By Selection view in the TOC Currently selected layers Currently selectable layers Currently not selectable layers Click to change selectability Number of selected features

7-4 Introduction to ArcGIS Create New Selection Add to Current Selection Remove from Current Selection Select from Current Selection Shortcuts: Using Select Features tool and.. Ctrl Key – unselects previous selected features and can select from the currently selected set Shift Key – add features to currently selected and remove features from current selection Interactive Selection Methods

7-5 Introduction to ArcGIS Query – Select By Attribute Identify Layer Identify selection method –Last selection method used will be default Create SQL “where” clause –Simple to complex expression  Selection can be based on one attribute or multiple –Save and reload selection expression

7-6 Introduction to ArcGIS SQL ‘Where’ Clause Tips Strings are in single quotes Attribute names in double quotes except for personal geodatabases – attributes are in square brackets Wildcard Cards (all file types except personal geodatabases) –% for one or multiple characters – ‘-’ for one character Personal Geodatabase wildcards – * for one or multiple characters – ? For one character More Tips found in ‘Select by Attribute’ Help Button

7-7 Introduction to ArcGIS Query - Select by Location Also known as spatial query Selecting features based on spatial relationship to other features in different or same layer

7-8 Introduction to ArcGIS Location Selection Methods Select by Location method options –Intersect –Within a distance –Are Within –Are Completely Within –Contain –Touch Boundary –Are Centered in –More…

7-9 Introduction to ArcGIS EPA Spatial Queries May need a series of queries to answer GIS question –Which TRI sites that have lead emissions are within 20 miles of a school? –Which NPL sites in Illinois are within the flood extent of the 2008 Mississippi Floods? –What is the population density 10 miles from my site and what languages are spoken?

7-10 Introduction to ArcGIS Select by Graphic Use a graphic to select features interactively 1) Draw graphic 2) Select by graphic

7-11 Introduction to ArcGIS Analytical Process Define the problem Define the criteria Identify the data you need Plan the analysis Prepare the data for analysis Execute the analysis Examine and present the results

7-12 Introduction to ArcGIS Bookmarks Save view in display area to return to it at any time Data frame specific –Can be shared between data frames by exporting to.dat file to My Places

7-13 Introduction to ArcGIS My Places My Places dialog box lets you create and work with a list of your most frequently used or favorite addresses, locations, features, and spatial extents. Data Frame and Map Document independent Launch My Places from Data Frame Tools toolbar

7-14 Introduction to ArcGIS Additional Windows Magnifier – see more detail without changing display –Move over display – change magnification Viewer – maintains view Overview – full extent of data with extent box of data view –As you pan or zoom around extent box changes as well

7-15 Introduction to ArcGIS Customizing the ArcMap Window Customize > ArcMap Options: –General Tab  Set new data visible on or off  Return to last used location when Add Data first used –Tables Tab  Change fonts, selected records color –Layout View Tab  set snap elements for guides, grid etc..