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Difference in DATEs
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* Difference in DATEs
@ 2004-09-21 07:38 Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>
  2004-09-21 14:01 ` Re: Difference in DATEs Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 1 reply; 3+ messages in thread

From: Dean Gibson (DB Administrator) @ 2004-09-21 07:38 UTC (permalink / raw)
  To: pgsql-sql

Assume that x and y are of type DATE:

1. AGE( x, y ) < INTERVAL '...' works.

2. x < y + INTERVAL '...' works.

3. x - y < INTERVAL '...' doesn't work (but then, the minus operator is not 
defined in the manual for two DATE values).

Question:  Is the meaning of x - y well-defined?  That is, is there a 
definition that I can count on?

Not an important question, but I'm curious, since I like to write date 
differences in a style that makes readability/maintenance easy.

-- Dean




^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Difference in DATEs
  2004-09-21 07:38 Difference in DATEs Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>
@ 2004-09-21 14:01 ` Tom Lane <tgl@sss.pgh.pa.us>
  0 siblings, 0 replies; 3+ messages in thread

From: Tom Lane @ 2004-09-21 14:01 UTC (permalink / raw)
  To: Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>; +Cc: pgsql-sql

"Dean Gibson (DB Administrator)" <postgresql3@ultimeth.com> writes:
> 3. x - y < INTERVAL '...' doesn't work (but then, the minus operator is not 
> defined in the manual for two DATE values).

Sure it is: see 10th row in
http://www.postgresql.org/docs/7.4/static/functions-datetime.html#OPERATORS-DATETIME-TABLE

Forget the interval and compare to an integer.

			regards, tom lane



^ permalink  raw  reply  [nested|flat] 3+ messages in thread

* Re: Difference in DATEs
@ 2004-09-21 15:53 Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>
  0 siblings, 0 replies; 3+ messages in thread

From: Dean Gibson (DB Administrator) @ 2004-09-21 15:53 UTC (permalink / raw)
  To: pgsql-sql

Tom Lane wrote on 2004-09-21 07:01:
>Sure it is: see 10th row in
>http://www.postgresql.org/docs/7.4/static/functions-datetime.html#OPERATORS-DATETIME-TABLE
>
>Forget the interval and compare to an integer.

Thanks;  that line is not present in the table in the 7.3.4 docs.

-- Dean




^ permalink  raw  reply  [nested|flat] 3+ messages in thread


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2004-09-21 07:38 Difference in DATEs Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>
2004-09-21 14:01 ` Tom Lane <tgl@sss.pgh.pa.us>
2004-09-21 15:53 Re: Difference in DATEs Dean Gibson (DB Administrator) <postgresql3@ultimeth.com>

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