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
}
		try
		{
			Image image = tableImage;
		
			if ( tablesRs != null )
			{
				int numberOfTable;
				
				Preferences preferences = JdbcPlugin.getDefault( ).getPluginPreferences( );
				if ( preferences.contains( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA ) )
				{
					numberOfTable = preferences.getInt( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA );
				}
				else
				{
					numberOfTable = DateSetPreferencePage.DEFAULT_MAX_NUM_OF_TABLE_EACH_SCHEMA;
					preferences.setValue( DateSetPreferencePage.USER_MAX_NUM_OF_TABLE_EACH_SCHEMA,
							numberOfTable );
				}
				int count = 0;
				while ( tablesRs.next( ) && count < numberOfTable )
				{
					String tableName = tablesRs.getString( "TABLE_NAME" );
					String type = tablesRs.getString( "TABLE_TYPE" );
					if ( type.equalsIgnoreCase( "SYSTEM TABLE" ) )
						continue;
					
					
					int dbType = DbObject.TABLE_TYPE;