Q&A for community managers, administrators, and moderators
with users as ( -- users who asked a question with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, creationdate), 0) date, OwnerUserId user_id from posts where creationdate < '2020-08-01' and creationdate >= '2020-07-01' and tags like '%julia%' union all -- users who answered to the questions with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, p2.creationdate), 0) date, p2.OwnerUserId user_id from posts p1 left join posts p2 on p1.id = p2.parentid where p2.creationdate < '2020-08-01' and p2.creationdate >= '2020-07-01' and p1.tags like '%julia%' union all -- users who made an edit to the questions with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, LastEditDate), 0) date, LastEditorUserId user_id from posts where LastEditDate < '2020-08-01' and LastEditDate >= '2020-07-01' and tags like '%julia%' union all -- users who made an edit to the answers of questions with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, p2.LastEditDate), 0) date, p2.LastEditorUserId user_id from posts p1 left join posts p2 on p1.id = p2.parentid where p2.LastEditDate < '2020-08-01' and p2.LastEditDate >= '2020-07-01' and p1.tags like '%julia%' union all -- users who commented under questions with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, c.creationdate), 0) date, c.userid user_id from posts p join comments c on p.id = c.postid where c.creationdate < '2020-08-01' and c.creationdate >= '2020-07-01' and p.tags like '%julia%' union all -- users who commented under answers to questions with the given tag select DATEADD(DAY, DATEDIFF(DAY, 0, c.creationdate), 0) date, c.userid user_id from posts p2 right join posts p1 on p1.id = p2.parentid join comments c on p2.id = c.postid where c.creationdate < '2020-08-01' and c.creationdate >= '2020-07-01' and p1.tags like '%julia%' ) select date, 'Julia' programming_language, count(distinct user_id) distinct_users_count from users group by date