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Re: compare date in two rows

From: "Oliveiros d'Azevedo Cristina" <oliveiros(dot)cristina(at)marktest(dot)pt>
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 (view raw or flat)
Thread:
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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Subject: Extract from date field
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