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
> pgman@candle.pha.pa.us | (610) 853-3000
> + If your life is a hard drive, | 830 Blythe Avenue
> + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
>
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
