Erik Jones wrote:
T E Schmitz wrote:
Gary Stainburn wrote:
On Friday 07 July 2006 14:51, T E Schmitz wrote:
I would like to split the contents of a column using substring with a
regular expression:
The column contains something like
"150mm LD AD Asp XR Macro"
I want to split this into
"150mm", "LD AD Asp XR Macro"
select substring('150mm LD AD Asp XR Macro','^\\d+mm') as BASE_NAME,
substring('150mm LD AD Asp XR Macro','^\\d+mm (.*)$') as SUFFIX;
base_name | suffix
-----------+--------------------
150mm | LD AD Asp XR Macro
(1 row)
The brackets surround the required match
But that takes me to the next problem:
For the sake of the example I simplified the regular pattern.
In reality, BASE_NAME might be:
28mm
28-70mm
So the reg. expr. requires brackets:
substring (NAME, '^(\\d+(-\\d+)?mm)' ) as BASE_NAME
Will the mm always be the end of the base name?
I had thought it best to simplify the problem for the purposes of the
mailing list but maybe I should supply the complete problem and describe
the purpose of the exercise:
I am trying to come up with a semi-automatic solution to tidy up some
data. If it's got to be done manually via the GUI it would mean a lot of
dummy work [for the customer].
First of all I did a 5 table join to select those NAMEs which don't
follow the required pattern: the pattern describes a photographic lens
(focal length followed by lens speed (aperture)) and nothing else.
Unfortuantely, there are a few hundred occurences where a few attributes
have been appended which should have been stored elsewhere.
valid entries would be:
"28mm F2.8" (prime lens)
"30-70mm F4" (zoom lens)
"30-70mm F2.8" (zoom lens)
"30-100mm F4.5-5.6" (zoom lens with variable speed)
In the WHERE clause I have specified all those NAMEs, which follow that
pattern but have some gubbins appended:
WHERE NAME ~
'^((\\d+(-\\d+)?)mm F((\\d+(\.\\d+)?)+(\.(\\d+(\.\\d+)?)+)?))\\D+$'
which gives me a listing of those candidates that need to be amended -
manually or otherwise.
Next, I wanted to produce a result which splits NAME into what it should
be (BASE) and attributes (SUFFIX). Maybe I can generate some SQL from
that to tidy up the data.
--
Regards,
Tarlika Elisabeth Schmitz
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