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So, there's an idea I had ...

Tags that are very old and have a low number of questions, are probably not really useful.

... which made me want to write a query for checking them out.

Wait, what... There's no field to access the creation date of the tag!

Can the tag creation date be added to the Data Explorer and to the SE API?

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1  
Why don't you just look up the creation date of the earliest post associated with that tag? – user184498 Aug 25 '12 at 23:43
1  
@BryanDunsmore It might've been removed from an earlier post, or added to that old post much later – Michael Mrozek Aug 26 '12 at 2:56
    
@MichaelMrozek What I would do then is to go through the suggested edits and see if any of them has an earlier date where the tags are edited. – user184498 Aug 26 '12 at 3:31
    
@BryanDunsmore: It would spare a lot of work if we just had a field instead of having to do a double join... – Tom Wijsman Aug 26 '12 at 11:23
    
@BryanDunsmore You'd need to find the earliest tag creation or tag edit that contains the tag, rather. But this only works if the post hasn't been deleted. – Gilles Aug 26 '12 at 11:49
    

In SEDE the Wiki and Excerpt are stored in the Posts table (posttypeid 3 and 4). You can take the creationdate of either the Wiki or the Excerpt of the tag. By joining the excerptpostid or wikipostid from the tags table to the posts table we can find the post creationdate which happens to be equal to the tag creationdate.

There is still one caveat with this: if the tag is deleted, so are the wiki and excerpt posts. The date you get here so to say not the first ever occurrence of the tag but the creationdate of the tag in its current life-time.

I used that technique in this query:

select t.tagname
     , t.count
     , case 
       when excerpt.creationdate < wiki.creationdate 
       then excerpt.creationdate
       else wiki.creationdate 
       end [creationdate]
from tags t
inner join posts excerpt 
        on excerpt.id = t.excerptPostid
inner join posts wiki
        on wiki.id = t.wikiPostid
order by count asc
       , case 
       when excerpt.creationdate < wiki.creationdate 
       then excerpt.creationdate
       else wiki.creationdate 
       end asc

This renders as of today the following result:

tags with creationdate

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