Re: compare date in two rows - Mailing list pgsql-novice

From Oliveiros d'Azevedo Cristina
Subject Re: compare date in two rows
Date
Msg-id 26B13197D5C34FBE95B39540CE89993E@marktestcr.marktest.pt
Whole thread Raw
In response to compare date in two rows  (LALIT KUMAR <lalit.jss@gmail.com>)
List pgsql-novice
Does your table has a primary key, or does it have just those three columns?
----- Original Message -----
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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