select
age.AGE_NAME as 年齢階層,
-- CASE WHEN [条件] THEN [条件を満たしたら表示する内容]　ELSE [条件を満たしていなかったら表示する内容]　END
-- as以降が数字で始まる時は””で囲む
sum(case when time.TIME_CODE = 120 then dtl.TARGET_POP else 0 end) as "5時間未満",
sum(case when time.TIME_CODE = 130 then dtl.TARGET_POP else 0 end) as "5時間以上6時間未満",
sum(case when time.TIME_CODE = 140 then dtl.TARGET_POP else 0 end) as "6時間以上7時間未満",
sum(case when time.TIME_CODE = 150 then dtl.TARGET_POP else 0 end) as "7時間以上8時間未満",
sum(case when time.TIME_CODE = 160 then dtl.TARGET_POP else 0 end) as "8時間以上9時間未満",
sum(case when time.TIME_CODE = 170 then dtl.TARGET_POP else 0 end) as "9時間以上",
sum(case when time.TIME_CODE = 180 then dtl.TARGET_POP else 0 end) as 不詳

from
SLEEP_TIME_DTL as dtl
inner join AGE_GRP as age
on dtl.AGE_CODE = age.AGE_CODE
inner join SLEEP_TIME as time
on dtl.TIME_CODE = time.TIME_CODE

group by 
age.AGE_NAME

order by
age.AGE_CODE;