public function InsertRelation( \rstoetter\libsqlphp\cKEY_COLUMN_USAGE_Entry $obj ) {

        if ( is_null( $obj->m_TABLE_NAME ) ) {
            die( "\n cKEY_COLUMN_USAGE_Entry mit is_null( m_TABLE_NAME ) " );
        }
	
        $obj_found = $this->SearchByKey( $obj->m_TABLE_NAME );
        if ( $obj_found === false ) {            
        
            // if the referencing table does not exist, then insert it in the tree
        
            $obj_new = new cKeyColumnUsageTreeNode( $obj->m_TABLE_NAME );
            
            if ( ! is_null( $obj->m_REFERENCED_TABLE_NAME ) ) {
                $obj_new->GetData( )->AddReferredTableName( $obj->m_REFERENCED_TABLE_NAME );
            }
            
            $this->InsertNode( $obj_new );
            
		} else {
		
            // if the referencing table does exist, then update its references
		
            if ( ! is_null( $obj->m_REFERENCED_TABLE_NAME ) ) {
                $obj_found->GetData( )->AddReferredTableName( $obj->m_REFERENCED_TABLE_NAME );
            }
		}
		
		// if the target table does not exist, then insert it in the tree
		
		if ( ! is_null( $obj->m_REFERENCED_TABLE_NAME ) ) {
		
            $obj_ref = $this->SearchByKey( $obj->m_REFERENCED_TABLE_NAME );
            if ( $obj_ref === false ) {            
                $obj_new = new cKeyColumnUsageTreeNode( $obj->m_REFERENCED_TABLE_NAME );
                $this->InsertNode( $obj_new );
            }
		}
		
	}