SELECT case when pmc=0 then null else cast(amc AS decimal(15,4))/cast(pmc AS decimal(15,4)) end am_pm_ratio

FROM

(SELECT count(*) amc

FROM web_sales,

household_demographics,

time_dim,

web_page

WHERE ws_sold_time_sk = time_dim.t_time_sk

AND ws_ship_hdemo_sk = household_demographics.hd_demo_sk

AND ws_web_page_sk = web_page.wp_web_page_sk

AND time_dim.t_hour BETWEEN 8 AND 8+1

AND household_demographics.hd_dep_count = 6

AND web_page.wp_char_count BETWEEN 5000 AND 5200) "at",

(SELECT count(*) pmc

FROM web_sales,

household_demographics,

time_dim,

web_page

WHERE ws_sold_time_sk = time_dim.t_time_sk

AND ws_ship_hdemo_sk = household_demographics.hd_demo_sk

AND ws_web_page_sk = web_page.wp_web_page_sk

AND time_dim.t_hour BETWEEN 19 AND 19+1

AND household_demographics.hd_dep_count = 6

AND web_page.wp_char_count BETWEEN 5000 AND 5200) pt

ORDER BY am_pm_ratio

LIMIT 100;