ANSI join types

I got this list from Gavin Roy's presentation at O'Reilly. Is there a
good spot for this summary?

Also, I can not find documentation on UNION JOINS in our docs.

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Bruce Momjian wrote:

SELECT
* JOINS

* Cross: All combinations of rows are used
* Inner: Only rows where matches are found are retained
* Left (Outer): Returns all rows from table A, matched or not, and
only rows from table B where matches are found
* Right (Outer): Inverse of Left, returns all rows from table B and
only matches from table A
* Full: A combination of left and right. Where matches are not
found, NULLs fill the columns of the other table
* Union: This is different than the UNION operator used to merge the
output of multiple queries. This is the inverse of an Inner, only
rows are returned when no matches are found

-- 
Bruce Momjian                        |  http://candle.pha.pa.us
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