I have one question -
I posed a question on our technical tests for new DBA/Developers and I asked
"Name All Types of join you are aware of"
The question was deliberatly loosely worded as I was looking to see how deep the person's understanding of joins was
I was looking for
Logical = Inner, Left/Right/Full outer , Cross Apply
Physical = Hash, Merge, Loop
this would demonstrate they understood not only the function of the join, but how the SQL engine behaves and physically performs these joins.
Now when we recruit in india I always get SELF JOIN added to the answers (but never in the UK for some reason)- I immediatly scratch this answer off as incorrect - but should i???
In the example SELF join actually used the INNER JOIN syntax - it does not matter which tables you join together it is still an INNER JOIN...
how about if the "self join" used a left OUTER??? is it still a self join? nope - it's a left outer (In my opinion)
Any thoughts??? In My opinion "SELF JOIN" is a nickname , but it does not functionally describe the join itself (ie you don't know if it's left , right, inner or outer"
Mike Vessey
MVDBA