Re: Random Number SKU Generator

I found one issue,
The leading zeros are removed. expected number "00042" printed "42"

Regards
Peter
 
 

Sent: Saturday, February 14, 2015 at 9:23 PM
From: "Peter Dabrowski" <meritage(at)mail(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Subject: Re: [NOVICE] Random Number SKU Generator

Thank you Roxane,
Applied the code against db, it is generating Random SKU and I did not to have any errors to report.
So far i'ts very good.
Best Regards
Peter
 

Sent: Saturday, February 14, 2015 at 2:20 AM
From: "Roxanne Reid-Bennett" <rox(at)tara-lu(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Subject: Re: [NOVICE] Random Number SKU Generator

On 2/13/2015 4:46 AM, Peter Dabrowski wrote:

I use a Luhn algorithm to generete random number, inserted below sql code to column 'SKU"
 
ALTER TABLE m_product ALTER sku SET DEFAULT ltrim(to_char(luhn_generate(round(random()*10000)::int), '00000'))
 
as a result on record saving random number is generated, but my problem is the numbers are not unique.
 
Somone sugest that I  should write a function to encapsulate "ltrim(to_char(luhn_generate(
round(random()*10000)::int), '00000'))"  and at the same time, check if the value is already used in the table.
 
in pseudo code it would look something like this:
 
generateMProductSKU(){
    skuGen=""
    needToGenerate = true
    while(needToGenerate){
      skuGen = ltrim(to_char(luhn_generate(round(random()*10000)::int), '00000'))
      if((Select count(*) from M_Product where sku =skuGen) = 0
         needToGenerate =  false
   }
   return skuGen
}
 
Culd somebody help me tu structure code into right sql format so it could be inserted into database.
 
Thank you very much.
Peterperhaps this?

create or replace function generateMProductSKU()
RETURNS text AS
$BODY$

DECLARE
    skuGen text;
    needToGenerate boolean;
BEGIN
    skuGen := '';
    needToGenerate := true;

    WHILE needToGenerate LOOP
        skuGen := ltrim(luhn_generate(round(random()*10000)::int)::text, '00000');
        SELECT count(*) != 0 into needToGenerate from m_product where sku = skuGen;
    END LOOP;

    return skuGen;
END
$BODY$
  LANGUAGE 'plpgsql' STABLE;

ALTER TABLE m_product ALTER sku SET DEFAULT generateMProductSKU();
 
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