On 03/27/2017 09:03 AM, Brian Dunavant wrote:
That does not return the correct answer for the original poster's request.
flpg=# select position('om' in reverse('Tomomasaaaaaaaaaaa'));
position
----------
15
(1 row)
It shows the position counting back from the end. If you want counting
from the front:
aklaver@test=> select (length('Tomomasaaaaaaaaaaa')+ 1) - position('om'
in reverse('Tomomasaaaaaaaaaaa'));
?column?
----------
4
On Mon, Mar 27, 2017 at 11:43 AM, Adrian Klaver
<adrian.klaver@xxxxxxxxxxx> wrote:
On 03/27/2017 08:05 AM, Ron Ben wrote:
Hi,
position(substring in string)
as listed here:
https://www.postgresql.org/docs/9.1/static/functions-string.html
locates sub string in a string.
It doesn't support locateing the substring from the back.
For example:
position('om' in 'Tomomas')
gives 2
But if I want to locate the first occurance from the back of the string
it's impossible/
aklaver@test=> select position('om' in reverse('Tomomas'));
position
----------
4
My suggestion is to create a function
position(substring in string,order)
where order can be: begin, end
and it will find the string according to this parameter.
This is pretty easy to implement and should be a part of the PostgreSQL
tools.
similar fuctionality exists in trim function where user can specify
leading or taling parameter
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Adrian Klaver
adrian.klaver@xxxxxxxxxxx
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Adrian Klaver
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