Eyes in the Sky II > GIT Web Course > Module 2 > Week 5 > Getting to Know Querying in GIS > Getting to Know Querying in My World

Week 5: Monitoring Invasive Species

Week 5: Monitoring Invasive Species

Getting to Know Querying in My World

Learn to create and execute GIS database queries to investigate the spread of zebra mussels.

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Launch My World, Open the Invasive Species Project File, and Add a New Layer

My World Icon
  • Launch My World by double-clicking its icon on your desktop or by clicking its icon in the dock (Mac) or Launch Bar (Win).
  • Choose File > Open Project, navigate to .../My World/data/Invasive_SpeciesMW and select the file inv_spc.m3vz. Then click Open.
  • construct mode selected
  • Add a new layer to show the sightings of the invasive zebra mussels. In Construct mode, switch to the "Invasive Species" Data Library. Double click the Layer's name "Zebra Mussel" and it will automatically be added to the top of the Layer List.
    Select the Invasive Species Data Library from the drop down menu. invasive species data library

  • Zebra Mussel should now be the top layer on your map. Notice that the layer is automatically turned on when it is added.
    In this view, the Zebra Mussel layer has been added. It is colored green, your color may be different. For now, don't worry about color!
    51 zebra mussels added
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Adding layer Video
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Zebra mussels; Dreissenna Polymorpha

Zebra mussels are small shellfish named for the striped color of their shells. They typically attach to objects by threads on their shells. The zebra mussel is native to the Black, Caspian, and Azoz Seas. They were first described in Europe, by Pallas, in 1769.

small zebra mussel image Zebra Mussel

Zebra mussels were first discovered in the Great Lakes of North America in 1988. It is likely that their introduction was due to a ballast exchange from a cargo ship. By 1990 they had spread rapidly to all of the Great Lakes. Soon thereafter they escaped to the Illinois and Hudson Rivers, eventually moving into the Mississippi River system. By 2008, Zebra Mussels had spread across the United States, all the way to California.

Zebra mussels are a significant invader because they can spread both in and out of the water. In their freshwater habitat they can disperse in all life stages. They are prolific biofouling agents and therefore have profound effects on water supply pipes, including nuclear power plant cooling intake pipes. Not only do they damage man made structures, they are disruptive to entire food webs. Zebra mussels primarily consume phytoplankton. Additionally, they consume other suspended materials in the water column. Consequently, areas with dense invasions of zebra mussels have unusually transparent water. In fact, during the invasion of zebra mussels in Saginaw Bay, Michigan the sampling areas experienced a 60-70% reduction in Chlorophyll –a concentrations.

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Adjust the Layers and Zoom in to the Zebra Mussel layer

  • Switch back to Visualize Mode. visualize mode selected
  • Turn on the U.S. States and U.S. Rivers layers.
    The U.S. States and U.S. Rivers layers are on.
    52 US rivers on zoom to active
  • Make U.S. Rivers the active layer buy clicking once on its name in the Layer List. Then zoom to the extent of the U.S. Rivers layer by clicking the Zoom to Active Layer zoom to active layer button.

    1. Make U.S. Rivers the active layer by clicking once on its name in the Layer List.
    2. Click on the Zoom to Active Layer zoom to active layer button.
      52 US rivers on zoom to active
    3. This map is the result.
      53 US rivers zoomed in
  • Next, make Zebra Mussel the active layer by clicking once on its name in the Layer List.
  • Click the Zoom to Active Layer zoom to active layer button to zoom to the current extent of the zebra mussel invasion.
    The map shows the extent of the zebra mussel invasion in the United States as of 2008.

    54 Zoom to active ZM
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Find A Feature By Its Attributes

The Find tool find button is a quick way to locate a feature. However, this type of search works best if you know how to spell, and capitalize, what you are looking for.
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Find the first zebra mussels in record from Ohio.

  • In to Visualize mode, visualize mode selected
  • Make Zebra Mussel the active layer by clicking once on its name in the Layer List.
  • Click once on the Zebra Mussel label in the Layer List. Then click the Show Table of Active Layer button. Spend some time looking through the fields and data records that are in the table. Use the scroll bars to move up and down and across the table. Look carefully at the STATE abbreviations.
    Here is the Table of Layer "Zebra Mussel" before scrolling.
    55 mussel table open


  • At the top of the Layer Table, click on the Find find button button.
  • In the Search Layer Table window that opens type in the abbreviation for Ohio, "OH". Check the "Case Sensitive" and "Match Whole Values Only" boxes.
  • Click Find Next. OH will be highlighted on the table.
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Use the Legend to find the U.S. State of Ohio

  • Turn on the Legend for the layer U.S. States by clicking the L symbol next to the words "Category List". On the legend for the layer U.S. States, click on the state name, Ohio. The state will be highlighted in yellow and a selection will show up in the Layer List.
  • Make the selection active by clicking the radio button next to its name and click the Zoom to Selection button to Zoom into the new selection for a closer look.
    1. Turn on the Legend for the Layer U.S. States by clicking the L symbol next to the words "Category List".
    2. On the legend for the layer U.S. States, click on the state name Ohio. The state will be highlighted in yellow and a selection will show up in the layer list. 56 ohio selected in legend
    3. Make the selection active by clicking the radio button next to its name and click the Zoom to Selection button to Zoom into the new selection for a closer look. 57 zoom to selected ohio
    4. The map is now zoomed to Ohio.
      58 zoomed into selected

  • When you are done exploring click the Zoom to Previous ExtentsZoom to Previous button.
  • In the Layer U.S. States, click the "All (highlighting off)", radio button.
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Question a Database with the Analyze Mode

The best way to find features, especially for larger or more complex searches is to Query the database in the table of the layer. In My World GIS this is done in the Analyze mode.
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Find all the zebra mussels sighted in the year 1988

  • Switch to Analyze mode, by clicking on the analyze button tab. A new window opens.
  • Switch to Analyze mode, by clicking the analyze button tab. A new window opens the window is pictured below. It may be empty at first until you begin your selections.
    59 empty analyse window
  • In the Analyze window click Select ... > By Value select by value .
    Set up the query to find records in the "Zebra Mussel" layer, that occurred in the year 1988. Do NOT make this selection a new layer; leave it as a subset of the original layer.
  • Use the pull down menus to Select Records from: Zebra Mussel, Whose YEAR is before 1989 CE and is On or After 1988 CE. To change the years click in the box with the year value and either use the up and down arrows or re enter the year value by typing in the new year.
  • Name the Result – Zebra Mussel 1988. Click OK.

  • 60 ZM analyze window
  • Five records are selected on the map and highlighted in the table of the selection.
  • On the layer name, in the Highlight Mode drop down, change the mode from "Color Selected Yellow" to "Hide Unselected".
    1. The Table of Selection shows five records selected after querying the zebra mussels layer for the year 1988.
      61 table of selected layer showing 5 records
    2. The query results are also highlighted on the map. But they are hard to see. 63 all records on map yellow dots hidden
    3. On the layer name, in the Highlight Mode drop down, change the mode from "Color Selected Yellow" to "Hide Unselected"
      62 hide unselected
    4. Now the Zebra Mussel records are showing in Ohio. 61 now can see the ZM in ohio
  • Repeat this process with several other years.
  • Click the Delete Selection button at the top of the Layer list to clear Selections from the Layer.
  • Be careful when doing this not to delete a layer. If you do accidentally delete a layer, return to Construct mode, use the Invasive Species Data library, and add the deleted layer back to the map.
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Find all the zebra mussel records from New York, NY.

  • In the Analyze window, click Select... > By Value . Select Records from Zebra Mussel, whose STATE is NY.
  • 427 records have been selected and are highlighted in yellow on the map. Click the Zoom to Selection button to zero in on NY State.
    67 state is NY map and table
  • Repeat this process with several other States.
  • Leave your selections in the layer list for now, you will use them in the next step.
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Put these two queries together to find all the zebra mussel records in the state of New York in the year 2005.

  • In Analyze mode, choose Select... > by Value
  • Select Records From Zebra Mussel whose YEAR is before 2006 and is on or after 2005. Click OK.
  • Next, click the "+" button to add a second equation to you query. Set up the second statement, Whose STATE is NY. Click OK.
    This selection should process have yielded only 1 result. Note: the "and" phrase in the middle of the Analyze window. It appeared when you clicked the "+" button. Querying is like setting up math equations or writing sentences. If you are confused, try reading your query out loud and see if it makes sense. This one reads "Show me the Zebra Mussel records whose Year is 2005 and whose State is New York. "
    69 state is NY 2005 analyse
    This image shows the query results in the table of selection and on the map. There is one dot in NY. To see it, choose the hide unselected highlight mode. Click on the image below for a larger view.
    70 State is NY map and table

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Set up a query to find a set of zebra mussels within the date range between 1997 and 2000.

  • The logic of the query is, "Show me the zebra mussel records from on or after 1997 but before 2001."
    The equation is Whose Year is before 2001 CE and Is On or After 1997. 71 analyse 97 -2001
    This image shows the query results on the map. In the table 808 records match the query and are highlighted in yellow on the map and listed in the table of the selection.
    71 map 97 -2001
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See how the zebra mussel invasion progressed over time

  • Execute the first query. In Analyze mode, Select... > By Value .
  • Select Records from: Zebra Mussel, Whose YEAR is before 1989 CE and is On or After 1987 CE. Name the Result: Zebra Mussel 1987 - 88. Click OK. Continue moving through the years to follow the invasion.
    The statement, Select Records from: Zebra Mussel, Whose YEAR is before 1989 CE and is On or After 1987 CE, produces 5 results highlighted on the map.
    73 anlyse window
    74 5 records on map
  • Leave the "Is On or After" setting the same, 1987, and change just the "Is Before" statement to see how the invasion changed over time.
  • How many zebra mussels had been documented by the end of 1988? 1990? 1999?
    The equation (YEAR < 1989) shows that 5 zebra mussels were documented by the end of 1988.
    The statement Whose: YEAR is Before 1990 and On or after 1987, shows that 20 zebra mussels were documented by the end of 1989.
    The equation YEAR is Before 2000 and On or After 1987 shows that 2354 zebra mussels were documented by the end of 1999.
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    Create and Explore More Database Queries

    Practice querying using combinations of set and Boolean operators, such as <, >, =, And, Or, Not, etc.

    Try the following:

    1. Use the Zebra Mussel layer to answer the question:
      Where are the zebra mussels that are in Ashtabula County AND Ohio?
      The equation is: Whose COUNTY is Ashtabula AND Whose STATE is OH
      The result of this query is 3 records.
    2. Substitute OR for AND in the equation above with the zebra mussel layer:
      The equation is: Whose COUNTY is Ashtabula OR Whose STATE is OH
      This query yields 95 records because it gives you BOTH records that are either in the county of Ashtabula or that are in the State of Ohio. The expression "OR" is more inclusive than the operator "AND".
    3. In the U.S. Rivers layer, try this equation that combines both set and Boolean algebra.
      Whose SYSTEM is Mississippi AND Whose LENGTHCOMP Greater than or Equal to 1361.4323989
      What question does this query answer?
      What rivers in the Mississippi River system have a length greater than or equal to 1361.43?
      Six rivers are selected.
    4. The U.S. States layer has interesting data to practice with.
      What happens when you enter this expression?
      Select Records from U.S. States, Whose Name Is Not Texas.
      The query shows all the U.S. States other than Texas. The result is listed as 50 States because the District of Columbia is included as a state.
    5. Try this equation with the U.S. States layer:
      Whose POPULATION 2000 is Greater Than or Equal to 1211537 AND Whose MEDIANAGE Less than 35.0
      What question does this query answer?
      What states have a population greater than 1211537 and a median age less than 35?
      Eleven states are selected.
    6. The wildcard symbol % combined with the expression LIKE allows you to set up a query that is a bit more open ended. Enter this equation in the Query Builder In the U.S. States layer:
      NAME Starts with A
      What result do you get and why?
      This query returns four states: AZ, AL, AR and AK. They are all the States that start with the letter A.
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    Build Your Own Database Query and Take a Screenshot

    Design and execute a query of interest to you or that you might use in your teaching. Here are a few suggestions.
    • Try selecting the U.S. Rivers, by Name, Length or System.
    • Select a Lake or River in your State.
    • Select your own State.
    • Select and combine attributes from the U.S. States layer such as population, number of farms, crop acreage or other demographic data.

    Once you have built and executed a query, take a screenshot of the map and the Analyze window. In your discussion group, post the question you asked, the statement you used, and the result of your query along with the screenshots. These are the screenshots that are needed for your required weekly activity.

    Follow the instructions below to make a screen shot:

    • On a Windows computer, press Alt and Printscreen at the same time. This will save an image of the screen to the computer's clipboard. Launch Paint and choose Edit > Paste. Save the image as a jpeg, giving it a name that describes it, such as River_query.jpg.

    • On a Mac computer, press Command-Shift-4 (Command key = Apple key) all at the same time and drag a box over the area of the screen that you want to capture. This will produce a file named Picture1.png on your desktop. Move Picture1.png to your Week 5 folder or to a place where you can easily find it. Double click on the file to open it in Preview. Rename the image and save it as a jpeg, giving it a name that describes it, such as River_query.jpg.
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    Explore More If You Have Time

    • Explore the Table of Layers of other layers in the map to see the rich assortment of data that can be found in a GIS.
    • Set up database queries that might interest you or your students.
    • Click and Drag to add other data layers to your map from the data layers that are built into My World and investigate these layers.
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    Resources


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    Movies on this Page

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    How to download movies

    • Click the link to go to the SERC media library listing for the movie. The record will open in a new window.
    • On the SERC media library page, right-click (Win) or control-click (Mac) the link (below the movie on the Flash version pages) to download the movie file to your hard drive.
    • Look below the movie window for the file download link.

      Save Movie from CMS listing

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    Flash Video Versions

    Download these versions to play on your computer. You'll need an appropriate movie player to view the file, such as Flash Player, Real Player (Mac / Win), or Adobe Media Player.

    Movie Icon Adding Layers My World

    Movie Icon Find Tool My World

    Movie Icon Query Builder My World

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    iPod Versions

    Download these version to play on your iPod or iPhone.

    Movie Icon Adding Layers My World

    Movie Icon Find Tool My World

    Movie Icon Analyze Mode in My World