Carsten, your example is very interesting. I didn't expect that 10 native funcs
calls can be 242 times faster (in a real/realistic use case)!
A suggestion: one can use macros. strip_digits() can become a macro, so the
code will be readable and there won't be performance problems. I use GNU m4
precompiler because I wasn't able to solve a problem with GCC.
An example from my macro lib.
Definition:
m4_define(<<EXECUTE_SQL>>, <<
SET @`$1` := '$2';
PREPARE `$1` FROM @`$1`;
m4_ifelse($3, <<CLOSE>>, <<SET @`>>$1<<` := NULL;>>)
EXECUTE `$1`;
m4_ifelse($3, <<CLOSE>>, <<DEALLOCATE PREPARE `>>$1<<`;>>)
>>)
Usage:
EXECUTE_SQL(stmt, <<SELECT 1;>>)
EXECUTE_SQL(stmt, <<SELECT 2;>>, CLOSE)
Regards,
Federico
--------------------------------------------
Gio 20/3/14, Carsten Pedersen <[email protected]> ha scritto:
Oggetto: Re: [Maria-discuss] help - i'm not finding one sql function
A: "Roberto Spadim" <[email protected]>, "Maria Discuss"
<[email protected]>
Data: Giovedì 20 marzo 2014, 09:50
On 19-03-2014 15:51,
Roberto Spadim wrote:
> hi guys, i'm
not finding a function to return how many character i
have,
> for example:
>
> "banana"
>
> i want a function
that return 2 "n" characters, example:
>
substr_count("banana","n") => 2
SELECT
CHAR_LENGTH(field)-CHAR_LENGTH(REPLACE(field, 'n',
''))
Many moons
ago, I blogged about something similar, performance
considerations and how to make your own
function:
http://www.bitbybit.dk/carsten/blog/?p=55
Best,
/ Carsten
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