>>>> 2013/10/22 12:20 -0400, >>>>
I recently upgraded a local MySQL installation to 5.5.32 and am trying to
figure out why the following query won't work as expected anymore. I'm just
trying to compare a set of dates to NOW() but since the upgrade, these don't
seem to work as expected.
SELECT
DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2 DAY),
NOW(),
DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2 DAY)<NOW()
For instance, when I run it on my system, I get 1 for the third column even
though comparing the two by eye it should be false.
<<<<<<<<
Well, show us all three columns....
And with 5.5.8 I get the same third column as you. Has it worked?
And I found that changed to
SELECT
DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2 DAY) AS
A,
NOW(),
CAST(DATE_ADD(STR_TO_DATE('2013-350-00:00:00','%Y-%j-%H:%i:%S'),INTERVAL 2 DAY)
AS DATETIME)<NOW() AS B
it works as hoped for--and it seems a bug to me, but probably an old one. It
seems to me that the outcome of DATE_ADD is DATE, not DATETIME, and the
comparison is numeric, with the six trailing 0s dropped. Quote about
STR_TO_DATE:
"It takes a string str and a format string format.
<file:///C:/Program%20Files/MySQL/MySQL%20Server%205.5/HELP/functions.html#function_str-to-date>STR_TO_DATE()
returns a
<file:///C:/Program%20Files/MySQL/MySQL%20Server%205.5/HELP/data-types.html#datetime>DATETIME
value if the format string contains both date and time parts, or a
<file:///C:/Program%20Files/MySQL/MySQL%20Server%205.5/HELP/data-types.html#datetime>DATE
or
<file:///C:/Program%20Files/MySQL/MySQL%20Server%205.5/HELP/data-types.html#time>TIME
value if the string contains only date or time parts. "
How really does it decide which type to return? It is wrong if the decision is
based whether all the hour, minute, and second are 0 or not.
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