[POBrien333]

The bug

Filtering the student list by course showed every student as having no activity — no completions, no active days — regardless of what they had actually done. The unfiltered list was always correct.

Cause

$wpdb->prepare() fills placeholders in SQL-text order. base_query() pushed parameters in the order the clauses were assembled. The course filter is appended to the activity subquery's WHERE, which sits after the three window comparisons in the SELECT list — so with a course filter every binding shifted by one:

completions_recent   event_time >= 8131            <- the course ID
active_days_long     event_time >= <short window>  <- wrong window
activity WHERE       course_id = 1781259752        <- a unix timestamp

No row has a course_id equal to a timestamp, so the subquery returned nothing, every student left-joined to NULL, and the list read as all zeroes.

The placeholder count still matched, so nothing errored. And the unfiltered shape — the only one exercised during development — was unaffected, which is why this reached a release.

Fix

Parameters are pushed in SQL-text order, with a comment on why assembly order and binding order differ.

Regression test

This is the second placeholder-ordering bug in this file, so a fix alone felt insufficient.

tests/placeholder-order.php substitutes parameters exactly as prepare() does and asserts each value is the right kind of value — timestamp comparisons get timestamps, course filters get post IDs — across six query shapes. No dependencies; runs with plain php.

• 9 failures against the 0.1.1 code
• 42/42 pass on this branch

.github/workflows/test.yml runs it plus a lint pass on PHP 7.4 and 8.3, on push and PR.

Also

• Bumped to 0.1.2 across the header, MSSA_VERSION and the readme stable tag
• tests/ excluded from the distributed zip — still 14 files
• Restored the missing 0.1.1 entry in readme.txt's changelog

Verifying after merge

Open the Student Activity screen, pick a course, and confirm students with recorded lessons in it now show their real figures.