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
namePattern = SQLUtility.getTailoredSearchText( searchTxt.getText( ) );
		  
		String dbtype = getSelectedDbType( );
		cachedDbType = dbtype;
		if ( dbtype != null )
		{
			if ( DbType.TABLE_STRING.equalsIgnoreCase( dbtype )
					|| DbType.VIEW_STRING.equalsIgnoreCase( dbtype ) )
			{
				tableType = new String[]{
					dbtype
				};
			}
		}
	    String catalogName = metaDataProvider.getCatalog();
		ArrayList tableList = new ArrayList();
	
		ResultSet tablesRs = null;
		ArrayList procedureRs = null;
		if (schemaName != null && schemaName.trim().length() > 0)
		{
			
			
			{
				if( metaDataProvider.isProcedureSupported() )
					procedureRs = metaDataProvider.getAllProcedure( catalogName, schemaName, namePattern );
				if( !DbType.PROCEDURE_STRING.equalsIgnoreCase(dbtype))
					tablesRs = metaDataProvider.getAlltables(catalogName,schemaName,namePattern,tableType);	
				tableList = new ArrayList();
				try