Re: Executing SQL expression from C-functions

Hello

see SPI interface

http://www.postgresql.org/docs/8.4/interactive/spi-examples.html

Regards

Pavel Stehule

2011/1/28 Jorge Arévalo <jorge(dot)arevalo(at)deimos-space(dot)com>:
> Hello,
>
> I need to write a C-function to extend my PostgreSQL server
> functionality. One of the arguments of that function is a string
> representing any PostgreSQL valid expression returning a number. For
> example:
>
> 3+5*cos(7.4)/8
> 7
> 2+2
> log(34)
> degrees(0.5)
> power(9.0, 3.0)
> case when 8 > 2 then 1 when 7*5 < 43 then 2 else 3 end
>
> and so on
>
> The point is my function first replace some values in the expression
> (variable names) for numbers and then it should execute the expression
> and returns the result (a number). With PL/pgSQL I can use EXECUTE
> expr INTO val, but how could I do it in a C function?
>
> Many thanks in advance, and best regards
>
> --
> Jorge Arévalo
> Internet & Mobilty Division, DEIMOS
> jorge(dot)arevalo(at)deimos-space(dot)com
> http://mobility.grupodeimos.com/
> http://gis4free.wordpress.com
> http://geohash.org/ezjqgrgzz0g
>
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