Saturday, January 26, 2013

SUM for strings in Oracle

At times I have needed in an aggregate function to build a list of varchar values in single row inside a group. Something like SUM aggregate function but for strings. I wanted to have for each group a list of strings separated by defined delimiter.

Monday, January 21, 2013

Parent/child dimensions in Jasper Analysis

Here I want to share my experience of using a dimension based on tree-like table. As database engine I used Oracle.

As known tree-like table is a table that has pair of columns, usually called as ID and PARENT_ID. Values of PARENT_ID column in children rows reference to values of ID column of their parents. Usually tree's element without any parent is called root, an element that has children is called node and an element without any children is called leaf.

Sunday, January 20, 2013

Simulation of outer joins in Jasper Analysis

JasperReports Server (Pentaho Mondrian behind the scenes) doesn't use outer joins when parses schema file to build analysis view. Today, at least.

Here I am describing the one of possible ways to change JasperServer behaviour as though it can handles outer joins. We don't have to make changes in any configuration, the solution just encloses manipulations with SQLs have used in schema definition.