Bug 124193 Parent axis doesn't work for recursive XPath
When table mapping for XML files is specified via recursive XPath: e.g. "//book", the parent axis access is broken for column mappings on such table: e.g. "../bookstore/@name" will not work. Same parent axis access works fine if non-recursive XPath is used for table mapping: e.g. "/bookstore/book".
data/org.eclipse.birt.report.data.oda.xml/src/org/eclipse/birt/report/data/oda/xml/util/RelationInformation.java
*/
	public int getBackRefNumber( String columnName )
	{
		return ( (ColumnInfo) this.columnInfos.get( columnName ) ).getBackRefNumber();
	}
	/**
	 * Return the defined data type of certain column.
	 * 
	 * @param columnName
	 * @return
	 */
	public String getType( String columnName )
	{
		return ( (ColumnInfo) this.columnInfos.get( columnName ) ).getColumnType( );
	}
	/**
	 * Return the hash map which defines the filters.
	 * 
	 * @return
	 */
	public HashMap getFilter( )
	{
		return this.filterInfos;
	}
	/**
	 * Add a column to a table.
	 * 
	 * @param ci
	 */
	public void addColumn( ColumnInfo ci )