Sry ....DoWhen is some thig like IF statment. it is the first acation in execution order. if the query written in the Do When action returns any rows then the subsequent actions will be executed.In a simple way DoWhen is a conditional actionDoSelect is a looping action
DoSelect : here we don't need to increase the counter. pointer to the next row in the selected data will be moved automatically.DoWhen: here we need to write the select query to skip the processed row.