B: Document history

The exact file history is recorded in the manual module in our CVS tree; see https://sourceforge.net/cvs/?group_id=9028.

Revision history

0.1	8 Apr 2005	PV	First edition.
0.2	15 Apr 2005	PV	Mentioned that Fb 2.0 legalises A = NULL” comparisons. Changed text in “Testing if something is NULL”. Slightly altered “Dealing with NULLs” section.
1.0	24 Jan 2007	PV	This is a major update, with so much new material added that the document has grown to around 4 times its former size. In addition, much of the existing text has been reorganised and thoroughly reworked. It's not feasible to give a summary of all the changes here. Consider this a new guide with 15–25% old material. The most important additions are:
			* NULL literals
			* IS [NOT] DISTINCT FROM
			* Internal functions and directives
			* Predicates: IN, ANY, SOME, ALL, EXISTS, SINGULAR
			* Searches (WHERE)
			* Sorts (ORDER BY)
			* GROUP BY and HAVING
			* CASE, WHILE and FOR
			* Keys and indices
			* CHECK constraints
			* SELECT DISTINCT
			* Converting values to NULL with NULLIF
			* Altering populated tables
			* Bugs list
			* Alphabetical index
1.0.1	26 Jan 2007	PV	Making non-nullable columns nullable again: Provisory fix of error regarding removal of NOT NULL constraints.