2018. 05. 07. 12:26 keltezéssel, Dimitry Sibiryakov s...@ibphoenix.com 
[firebird-support] írta:
> 07.05.2018 12:19, Gabor Boros mlngl...@bgss.hu [firebird-support] wrote:
>> A simple example: SELECT ''='' SIMILAR TO '[A-Z]{2}[0-9A-Z]{2,13}' FROM
>> RDB$DATABASE
>>
>> Why is the result true?
> 
>     Your expression is actually calculated as "CAST(''='' as CHAR(5)) SIMILAR 
> TO
> '[A-Z]{2}[0-9A-Z]{2,13}'".
>     (''='') is true and string representation of true is 'TRUE ' that matches 
> your patters.


Result of

SELECT  '*' || CAST(''='' AS CHAR(5)) || '*', 
CHARACTER_LENGTH(CAST(''='' AS CHAR(5))) FROM RDB$DATABASE

is

CONCATENATION  CHAR_LENGTH
============= ============
*TRUE *                  5

So I see what you say. But result of

SELECT CAST(''='' AS CHAR(5)) SIMILAR TO  '[A-Z]{2}[0-9A-Z]{2,13}' FROM 
RDB$DATABASE;

is

=======
<false>

So put the two case into one query

SELECT ''='' SIMILAR TO  '[A-Z]{2}[0-9A-Z]{2,13}', CAST(''='' AS 
CHAR(5)) SIMILAR TO  '[A-Z]{2}[0-9A-Z]{2,13}' FROM RDB$DATABASE;

and the result is

======= =======
<true>  <false>

And result of

SELECT 'TRUE ' SIMILAR TO  '[A-Z]{2}[0-9A-Z]{2,13}' FROM RDB$DATABASE

is

=======
<false>

Gabor


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  • [firebird-supp... Gabor Boros mlngl...@bgss.hu [firebird-support]
    • Re: [fire... Dimitry Sibiryakov s...@ibphoenix.com [firebird-support]
      • Re: [... Gabor Boros mlngl...@bgss.hu [firebird-support]
        • R... Dimitry Sibiryakov s...@ibphoenix.com [firebird-support]
          • ... Gabor Boros mlngl...@bgss.hu [firebird-support]
    • Re: [fire... liviuslivius liviusliv...@poczta.onet.pl [firebird-support]
      • Re: [... Gabor Boros mlngl...@bgss.hu [firebird-support]
    • Re: [fire... liviuslivius liviusliv...@poczta.onet.pl [firebird-support]

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