I want to count the number of distinct items in a column subject to a certain condition, for example if the table is like this:
tag | entryID
----+---------
foo | 0
foo | 0
bar | 3
If I want to count the number of distinct tags as "tag count" and count the number of distinct tags with entry id > 0 as "positive tag count" in the same table, what should I do?
I'm now counting from two different tables where in the second table I've only selected those rows with entryID larger than zero. I think there should be a more compact way to solve this problem.
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