diary at Telent Netowrks

Clé RIB validation#

Mon, 18 Oct 2004 12:59:23 +0000

Clé RIB validation

This may not be so interesting to most of my usual readers, but is added here in the hope that (a) Google will find it, (b) French Google users will be able to understand it. The French banking system has a thing called "Prélévement Automatique", which is essentially an authority for a third party to help themselves to your bank account at regular intervals. UK readers will recognise it as a Direct Debit; I'm sure other countried have similar things. To to set this up you need 23 characters of bank codes (5 char code banque, 5 char code guichet, 11 char numero de compte, 2 digits clé) , and it turns out that the last two of them are a checksum. I spent a while looking around web pages written in languages I have no particularly good grasp of (French, VB, PHP, some Clipper/Foxpro thing) looking for details on how to calculate it, and eventually transliterated a PHP example to arrive at the following:

create or replace function fr_calculate_cle(varchar,varchar,varchar) 
returns char(2) as '
        code_banque ALIAS FOR $1;
        code_guichet ALIAS FOR $2;
        num_compte ALIAS FOR $3;
        instring TEXT;
        cle integer;
        instring = translate(lower($1||$2||$3),
        cle := 62*to_number(substr(instring,1,7),''9999999'');
        cle := cle+ 34*to_number(substr(instring,8,7),''9999999'');
        cle := cle+ 3*to_number(substr(instring,15,7),''9999999'');
        return substr(to_char(97-(cle % 97),''00''),2);
' language 'plpgsql';

If there's any better way to make postgres output a 2 digit zero-padded number without a leading space, I want to hear about it.