Question

How to read DB table value and create an XML using custom logic?

Answer 1

Create a channel that uses a DB as the source.  Add your query to the SQL Stmnt section:

Set up a new output message as XML:

Create a new mapping function for your custom script. 

Here is some example code that will add the data from 'DBColumn1' of the source query into a <DBColumn1> XML node:

var value = source.getNode('DBColumn1');
message.setNode('/root/DBColumn1', value);
message.formatXML(3);

Because database sources provide a CSV message, the Recipes in QIE Help also have useful CSV mapping examples.