instruction: Number of active experts per week in a TAG (SO), parameterized.
response: SELECT t.TagName, COUNT(DISTINCT p.OwnerUserId) AS Users FROM Users AS u, Posts AS p, PostTags AS pt, Tags AS t WHERE p.OwnerUserId = u.Id AND p.PostTypeId = 2 AND p.Score > 0 AND pt.PostId = p.ParentId AND t.Id = pt.TagId AND (t.TagName = 'c' OR t.TagName = 'java' OR t.TagName = 'mysql' OR t.TagName = 'c#') GROUP BY t.TagName