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Archives of the TeradataForum
Message Posted: Fri, 12 Aug 2005 @ 09:28:55 GMT
| Subj: | | Re: ROWID based join! |
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| From: | | Victor Sokovin |
| | 1. Find avg sal by dept. -- I said -> sel avg(sal) from emp group by deptno. He insisted that deptno would have to be selected in the
select clause else an error will b thrown. I just tested it after coming back home and it did work!! Are there specific conditions where it
wouldnt -- like will work in BTET and not in ANSI or BTEQ & SQLA etc?? | |
It might work everywhere but it is kind of natural to include the column for which you calculate the average, no? Sheer curiosity rather than a
technical problem should be the reason for including the column in the SELECT list. I think you might have won the case in the court of appeal,
though. Is there such an institution for SQL exams these days?
| | 2. What is a ROWID based join? - I've come across rowhash based and rowkey based join -- but what is a ROWID based join? I just
sifted thru the materials i've got and tried some explain but couldnt find out. Is there such a join - anyone? | |
The only context I can think of is the definition of join indexes, where we could talk about such a join if ROWID is specified in the SELECT
list of the index. A rather internal piece of knowledge: one specifies ROWID in the SELECT, one gets that particular type of join. Not that one
can do anything about it. For whatever it might be worth, I don't think this is an essential thing to memorize.
Keep your chin up! If you have to redo the test, there is always a chance to learn something which you did not notice on the first read.
Regards,
Victor
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