From: | "Oliveiros d'Azevedo Cristina" <oliveiros(dot)cristina(at)marktest(dot)pt> |
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To: | "LALIT KUMAR" <lalit(dot)jss(at)gmail(dot)com>, <pgsql-novice(at)postgresql(dot)org> |
Subject: | Re: compare date in two rows |
Date: | 2011-06-17 11:10:33 |
Message-ID: | 26B13197D5C34FBE95B39540CE89993E@marktestcr.marktest.pt |
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Lists: | pgsql-novice |
Does your table has a primary key, or does it have just those three columns?
----- Original Message -----
From: LALIT KUMAR
To: pgsql-novice(at)postgresql(dot)org
Sent: Friday, June 17, 2011 11:17 AM
Subject: [NOVICE] compare date in two rows
Hi,
I have a table with following sample data.
Village_name Date Label
A 1991-01-31 0
A 1991-04-28 0
A 1991-07-15 0
B 2000-02-15 0
B 2000-04-13 0
B 2001-09-13 0
C 1995-07-12 0
C 1995-10-13 0
I need to update the label to 1 when the number of days between two dates(when compared with previous date) is greater than 120 for each village.
Illustration:
For village A: row 1 date will not be compared to any date.
row 2 date will be compared to row 1 date and if satisfies the condition label will be made 1.
row 3 compare to row 2 and continue this till last row for village A.
Similarly first date for village B,C.
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