Re: SELECT substring with regex

Rodrigo De Leon wrote:
> On 7/7/06, T E Schmitz <mailreg(at)numerixtechnology(dot)de> wrote:
>
>> 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
>>
>> Actually, the pattern is more complex than that and I cannot see how I
>> can express it without brackets.
>
>
> Maybe:
>
> select
> substring ('28-70mm LD AD Asp XR Macro', '^[\\d-]*mm' ) as BASE_NAME

Sorry, but that would also capture something like
10-30-59mm

The pattern describes either a single length (120 millimeters) or a
range (30 to 70 millimetres), hence:

\\d+(-\\d+)?mm

The ? quantifier refers to the combination of '-' and digits and has to
be bracketed.

If the brackets cannot be avoided in the expression, your original
suggestion might come in handy though:

SELECT
substring (NAME, '^\\d+(-\\d+)?mm') AS BASE_NAME ,
substr(
NAME
, char_length(
substring (NAME, '^\\d+(-\\d+)?mm')
) + 2
) AS SUFFIX

Still, I'd be interested to know whether there is a 'more elegant' solution.

--

Regards,

Tarlika Elisabeth Schmitz