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
if ( availableDbObjectsTree != null )
			availableDbObjectsTree.removeAll( );
	}
	
	/**
	 * Gets the list of schema objects
	 */
	private void getAvailableSchema( )
	{
		if ( isSchemaSupported )
		{
			ResultSet schemas = metaDataProvider.getAllSchema( );
			schemaList = getAllSchemaList( schemas );
		}
	}
	
	/**
	 * 
	 * @param schemaName
	 * @param schemaTreeItem
	 */
	protected void populateTableList( String schemaName ,TreeItem schemaTreeItem )
	{
		if ( schemaTreeItem != null )
		{
			removeTreeItem( schemaTreeItem );
		}
		String namePattern = null;
		String[] tableType = null;
		cachedSearchTxt = searchTxt.getText( );