Bug 161191 Null is inserted when drag columns to query text with ctrl key pressed
Description: Null is inserted when drag columns to query text with ctrl key pressed Steps to reproduce: 1. New a data source. 2. New a dataset. 3. Press and hold ctrl key, select OFFICECODE and CITY columns, drag to query text. Expected result: "CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted in query text. Actual result: "null,CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
{
				Object obj = selection[i].getData( );
				
				if ( obj instanceof DbObject )
				{
					data += SQLUtility.getDnDString( ( (DbObject) obj ).getName( ),
							identifierQuoteString,
							identifierQuoteStringCheckBox.getSelection( ) );
				}
				
				else if ( obj instanceof Procedure )
				{
					data += SQLUtility.getDnDString( ( (Procedure) obj ).getProcedureNameWithSchema( ),
							identifierQuoteString,
							identifierQuoteStringCheckBox.getSelection( ) );
				}
				
				else
				{
					data += SQLUtility.getDnDString( obj,
							identifierQuoteString,
							identifierQuoteStringCheckBox.getSelection( ) );
				}
				data += i != selection.length - 1 ? "," : "";
			}
			event.data = data;
		}
	}
	/**
	 * Adds drop support to viewer.Must set viewer before execution.