Saturday, April 10, 2010

Intercept null value on a query

These last days working to create a Pentaho report with openERP data, I came across a serious problem:
if a query return a null value arithmetic operations are in error. The question was how to intercept the null value, surfing on Google I found this
SELECT IFNULL (1,0) this query return 1
SELECT IFNULL(null, 0) this query return 0
Fine my problem was solved NO!!  openERP use postgresql and postgresql doesn't support IFNULL
Again surfing on Google and I found COALESCE
The postgresql manual say:
The COALESCE function returns the first arguments of ITS THAT IS NOT NULL. Returned is null only if all arguments are null. Often it is used to substitute a default value for null values 

Finally my problem was solved my query now  is something like this
SELECT COALESCE(sum(aal.amount * -1) , 0) FROM account_analytic_line AS aal WHERE (aal.account_id=83) and aal.journal_id = 3

Rinaldo

Thursday, April 8, 2010

5 Levels of Agile Planning: From Enterprise Product Vision to Team Stand-up

To day I need to suggest a paper that evaluates agile practices when applied in multi-team and multi-person-year projects. Download it here  


Rinaldo

Wednesday, March 31, 2010

Scaling Java EE Applications

In this article, Wang Yu takes real world cases as examples to explain ways on how to scale Java applications based on his experiences on the laboratory projects, and at the same time, bring together practice, science, algorithms, frameworks, and experience on failed projects, to help readers on building high scalable Java applications.