Novice question
Which of the following is/are valid closed vector polygon(s)?
a) ( (1,1), (2,2), (2,3) )
b) ( (1,1), (2,2), (2,3), (1,1) )
c) ( (1,1), (2,2), (2,3), (0,0) )
d) ( (1,1), (2,2), (2,6), (1,1) )
e) a and c
f) b and d
Expert question
You’re working on a project at a new employer, you’re seeing a problem where your group by sums from your GIS census data aren’t rolling up correctly in a query written by the previous employee. Some counties are reporting multiple times when you run your query.
The query you’ve inherited is:
select county_fips, sum(population), sum(college_grads) from census_data group by tractid, county_fips;
The table might look like:
featureid tractid county_fips state_fips population college_grads ---------- ---------- ----------- ---------- ---------- ------------- 1 1 001 40 2000 200 2 20 002 40 5000 60 3 20 002 40 13000 900 3 22 002 40 15342 73
What is the correct query to sum the two variables population and college_grads for each county_fips?
a) select county_fips, average(population), average(college_grads) from census_data group by tractid, county_fips;
b) select county_fips, total(population), total(college_grads) from census_data group by tractid, county_fips;
c) select county_fips, sum(population), sum(college_grads) from census_data group by county_fips;
d) select tractid, sum(population), sum(college_grads) from census_data group by tractid;