Re: Compare rows

On 13 July 2011 07:15, LALIT KUMAR <lalit.jss@gmail.com> wrote:
> Hi,
> I have the following table.
> city    Rate         flag
> A         10             0
> A         20             1
> A         30              0
> A          2              0
> A         23              1
> A        12               0
> B          5               1
> B          43              0
> C         23                1
> C        67                 1
> For every city I have so set the  flag as -1 in row which is 0 above the row
> having flag as 1.
> So my out would be:
> city    Rate         flag
> A         10             -1
> A         20             1
> A         30              0
> A          2              -1
> A         23              1   (not changed to -1 as it not 0)
> A        12               0  (not changed to -1 because i need to compare
>  it to row of same city. so being last row not compared with any row)
> ----------------------------------------------------
> B          5               1
> B          43
> C         23                1
> C        67                 1

There doesn't appear to be any particular order to your rows.

--
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company