CREATE TABLE foobar ( Who CHAR(1), When DATETIME);
...
INSERT INTO foobar ...
INSERT INTO foobar ...
...
SELECT Who, COUNT(DISTINCT who) FROM foobar GROUP BY who;
...

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Even a spreadsheet can do it.

In reply to Re: searching items in a row based on time and date by Anonymous Monk
in thread searching items in a row based on time and date by skytarget

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