Coincidentally, I found this bug just today also, and whilst
I acknowledge the workarounds if the only thing you need is the month,
sometimes you need the relative position within the month also.
I would suggest that the end of march's -1month would more intuitively
map to the end of february, repeated. ie, "lock" the month in, and
adjust the "least significant" part - the day.
Same sort of unintuitive results can occur with requesting +1 month, or
even +/-1year from February 29.
I also thought it might be illuminating to see how other systems handle
this ambiguity.
mysql> SELECT DATE_SUB('2012-03-31', INTERVAL 1 MONTH);
+------------------------------------------+
| DATE_SUB('2012-03-31', INTERVAL 1 MONTH) |
+------------------------------------------+
| 2012-02-29 |
+------------------------------------------+
1 row in set (0.00 sec)
Colleagues inform me that postgresql behaves this way also, alongside
python's mx.DateTime library (and ms-sql too).
Conversely, sqlite, php behave like 'date' :)
.../Nemo
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earth native
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earth native
