Undo

Retrieving data from the database and changing the data is really easy. But what, if the user changes data and want to do an UNDO?

Doing a new query is the easiest way. The limitations are:

- in a multi-record-block you have to position in the correct record after the query
- if the query was executed via ENTER-QUERY mode you can't jump to the old record because the query-result has changed.

So you have to use a new technique.

The solution is this function. All database-items get their old values back:

PROCEDURE Undo IS
  V_Block  VARCHAR2 (30) := :SYSTEM.CURSOR_BLOCK;
  V_Field  VARCHAR2 (61);
  V_Item   VARCHAR2 (61);
BEGIN
  Validate (Item_Scope);
  IF :SYSTEM.RECORD_STATUS = 'CHANGED' THEN
    V_Field := Get_Block_Property (V_Block, FIRST_ITEM);
    V_Item := V_Block || '.' || V_Field;
    WHILE V_Field IS NOT NULL
    LOOP
      IF Get_Item_Property (V_Item, ITEM_TYPE) 
         IN ('DISPLAY ITEM', 'CHECKBOX', 'LIST', 
             'RADIO GROUP',  'TEXT ITEM')
      AND Get_Item_Property (V_Item, BASE_TABLE) = 'TRUE' 
      THEN
        COPY (Get_Item_Property (V_Item, DATABASE_VALUE), 
              V_Item);
      END IF;
      V_Field := Get_Item_Property (V_Item, NextItem);
      V_Item := V_Block || '.' || V_Field;
    END LOOP;
  END IF;
END;

Best practice is to start this undo-procedure from a menu (e.g. EDIT - UNDO) or handle it through a shortcut.