title: SpagoBI Studio and BIRT Report with String Parameters does not work
body: <p>SpagoBI Studio BIRT fails to retrieve external data set definition when data set has a String parameter.</p>
  
  <p>I'd like to have an external data set with String parameters, defined in SpagoBI.  That data set uses the parameter in the query's WHERE clause.  I'd like to use SpagoBI Studio to design a BIRT report that use that same data set and properly pass the data set's required parameters. </p>
  
  <p>When I try to retrieve the External Data set definition (with parameters) into a BIRT report, I get an error and it fails to import the data set definition.
  If I remove those parameters from the data set, retrieving the data set definition works, but I no longer have parameters. </p>
  
  <p>If the External Data Set has String parameters which are used in the query's WHERE clause, then SpagoBI Studio / BIRT will fail when trying to attach/retrieve the data set. 
  I'm not able to get to the point where I can specify that null is a permissible value on the parameter in BIRT, because... it fails before it can display the data set fields, params, etc in BIRT</p>
  
  <p>When the External Data set has Numeric parameters, the whole scenario works fine but I'm limited to passing numeric parameters to drive record selection in the query.</p>
  
  <p>Please see the following JIRA. </p>
  
  <p>Studio Fails to import External Data Set where query has single quotes wrapping a parameter 
  <a href="http://www.spagoworld.org/jira/browse/SPAGOBI-1870" rel="nofollow">http://www.spagoworld.org/jira/browse/SPAGOBI-1870</a> </p>
  
  <p>Discussion of the issue on the forum, at <a href="http://www.spagoworld.org/jforum/posts/list/3187.page#10288" rel="nofollow">http://www.spagoworld.org/jforum/posts/list/3187.page#10288</a></p>