Article belongs to specific Article Type object.
To retrieve the
CreatedById, you need to retrieve from Knowledge Article version object which end with
SELECT Id,Title,UrlName,Summary,KnowledgeArticleId, CreatedById
WHERE PublishStatus ='Online' AND Language ='en_US'
AND KnowledgeArticleId = 'kA2160000005CpjCAE'
Moreover, there are also restriction firing the SOQL query:
When querying the Custom_Artile_Type__kav object,
you must filter using the following syntax:
Id = [single ID], Id IN [list of ID's] or Language = [language ISO code] or PublishStatus = [status]
In addition Language is only permitted in a top-level AND condition.
To retrieve Data Categories, you need to query from
SELECT Id, DataCategoryGroupName, DataCategoryName, ParentId
By the way, we cannot filter on
DataCategoryGroupName, DataCategoryName in the above SOQL query.
So, filter and matching should have to be done in apex coding.
For more information, refer Articles