Multiple statements can be chained one after the other using a semi-colon delimiter, where the results of the first statement are passed into the second and so on.
select sum(sent) as Sent, sum(opened) as opened, customer, month(date) as Month group by customer, month(date); select (opened/sent)*100 as Open Rate, Opened, Sent, Customer, Month; select round(Open Rate,1) as Open Rate, Opened, Sent, Customer, Month where Month > $c9_thisyear+2m and Open Rate > 20 order by Open Rate asc
a) gets the Total Sent and Opens on a monthly basis for each customer,
b) then calculates the open rate based on the data from previous step since March,
c) adds additional criteria along with rounding the open rate.