I need to create a subquery and join in Mysql workbench.

Use query from Step 9 as a subquery and join it to the demographics table using the following case statement:

demographics.age =

case

when temp_pop.age < 18 then '00 to 17'

when temp_pop.age > 64 then '65 to 80+'

else '18 to 64'

end

temp_pop is an alias for the subquery. Use the following calculation for the demand output:

round(sum(temp_pop.total_pop * demographics.coefficient)) as demand

Output the demand grouped by year and education level.

Step 9 query:

select year, age, pop_total from pop_proj