I'm trying to make a database of students using Google Sheets. It contains info about students, groups and orders; orders can change students membership in groups (taken in a group, moved up to a new group, graduated, on leave, sent down). Here are sample database sheets and here is a detailed description of my DB structure (the sheet report_Groups is slightly changed, its previous variant, described on the link, is now named old_report_Groups).
I need a query that would select a list of present members of given group on the given date. That means that for each student I have to select the name, the latter status before given date and corresponding group. And from this result select student names, where statuses are "Taken in" or "Moved Up" and group is the same as given one.
The problem is to select the latter status. It should be MAX(status), whose "since" date ≤ given date, but there's a well-known problem of selecting more than one field together with aggregate function. Here is a question which is very close to, but query from its "best" answer gives me error "QUERY:NO_COLUMN". I've even copied the sheet Raw from there and tried to perform proposed query (with the onliest modification — replacing commas with semicolons according to my locale restrictions) on the data it was reported to work on — same error (check Raw and report_Raw sheets in my DB). Other variant (via MMULT and TRANSPOSE) works, but it's perfomance is very poor.
What can you suggest me? Thanks in advance.
Update: I've found the solution with an issue (described in my answer). To solve the issue I need to know an answer for a different question.
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