Bug 123726 "Top n", "Bottom n" in highlight dialog doesn't work.
Description: "Top n", "Bottom n" in highlight dialog doesn't work. Steps to reproduce: 1. Add a highlight for a table. 2. Set highlight rule: "account_id", "top n", "3", let its font color red. 3. Preview the report, it doesn't work. Attached is design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
* @param groupSpecs
		 * @param i
		 */
		private int getTempComputedColumnType( int i )
		{
			int interval = i;
			if( interval == IQuery.GroupSpec.DAY_INTERVAL 
				|| interval == IQuery.GroupSpec.HOUR_INTERVAL
				|| interval == IQuery.GroupSpec.MINUTE_INTERVAL
				|| interval == IQuery.GroupSpec.SECOND_INTERVAL
				|| interval == IQuery.GroupSpec.MONTH_INTERVAL
				|| interval == IQuery.GroupSpec.QUARTER_INTERVAL
				|| interval == IQuery.GroupSpec.YEAR_INTERVAL
				|| interval == IQuery.GroupSpec.WEEK_INTERVAL )
				interval = DataType.DATE_TYPE;
			else if ( interval == IQuery.GroupSpec.NUMERIC_INTERVAL )
				interval = DataType.DOUBLE_TYPE;
			else if ( interval == IQuery.GroupSpec.STRING_PREFIX_INTERVAL )
				interval = DataType.STRING_TYPE;
			else
				interval = DataType.ANY_TYPE;
			return interval;
		}
	}
	
	/**
	 * Simple wrapper of colum information, including column index and column
	 * name.
	 */
	private static class ColumnInfo