Tom Lane 8f889b1083 Implement UPDATE tab SET (col1,col2,...) = (SELECT ...), ... ... This SQL-standard feature allows a sub-SELECT yielding multiple columns (but only one row) to be used to compute the new values of several columns to be updated. While the same results can be had with an independent sub-SELECT per column, such a workaround can require a great deal of duplicated computation. The standard actually says that the source for a multi-column assignment could be any row-valued expression. The implementation used here is tightly tied to our existing sub-SELECT support and can't handle other cases; the Bison grammar would have some issues with them too. However, I don't feel too bad about this since other cases can be converted into sub-SELECTs. For instance, "SET (a,b,c) = row_valued_function(x)" could be written "SET (a,b,c) = (SELECT * FROM row_valued_function(x))".		2014-06-18 13:22:34 -04:00
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src	Implement UPDATE tab SET (col1,col2,...) = (SELECT ...), ...	2014-06-18 13:22:34 -04:00
bug.template	Stamp HEAD as 9.5devel.	2014-06-10 21:36:13 -04:00
KNOWN_BUGS	Remove extra newlines at end and beginning of files, add missing newlines	2010-08-19 05:57:36 +00:00
Makefile	Remove maintainer-check target, fold into normal build	2013-10-10 20:11:56 -04:00
MISSING_FEATURES	Remove extra newlines at end and beginning of files, add missing newlines	2010-08-19 05:57:36 +00:00
TODO	Update URL.	2008-08-21 20:15:31 +00:00