From the course: Foundations of Geographic Information Systems (GIS)

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Asking a map questions

Asking a map questions - GIS Tutorial

From the course: Foundations of Geographic Information Systems (GIS)

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Asking a map questions

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Need to know where the water lines are that haven't been inspected lately? Where are all the buildings in the city that are in a floodplain? Just ask your GIS to show you. A GIS lets you pick through huge stacks of data to quickly answer complex questions. You ask a map a question by running a query. GIS software supports database queries using the structured query language or SQL: a standard language that's been used for decades. When you query a standard database, you get a list of records returned. When you query a geospatial database, you get the results displayed on a map instead of just in a list of records. Let me show you an example of how GIS queries are used. Look at this map that shows all of the oil and gas wells in the U.S. state of Louisiana. There are nearly 200,000 wells in the state. Some are still active, but many are old and no longer used. Suppose you wanted to find out how many of those wells are actually still producing oil. First, look at the table to see what…

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