Problem description: 
When I change the FIELD NAME and FIELD TYPE at once, the table is broken and thus causes data loss.

Steps to reproduce:

1. New base TABLE in design mode, Fields: 
ID (Integer, AutoVaule, Primary Key);
AGE (Tiny Interger).
Save.

2. OPEN the TABLE and insert a row of data:
AGE: 28
Save.

3. EDIT the TABLE fields:
change "AGE (Tiny Integer)" to "DATE_OF_BIRTH (Date)", save.
A warning message will show up and say "The column DATE_OF_BIRTH" could not be saved, and ask whether should the column be deleted and appended.

4. When choose NO, the FIELD NAME is back to "AGE" and the save button is greyed-out. Close the EDIT window.

5. OPEN the above TABLE to see the columns and rows. You will see the 2nd column is "DATE_OF_BIRTH" rather than "AGE". However, in TABLE design mode (EDIT), the 2nd column is still "AGE".

6. Do anything possible to correct the problem shown in step 5. You may find it's impossible. That is to say, the TABLE is broken, and your data is lost. (Base seems confused about whether the column is "AGE" or "DATE_OF_BIRTH".)

Current behavior:
Base is confused in step 3, and causes TABLE to be broken.


Expected behavior:
Base should accept the FIELD changes in step 3 correctly, and not cause TABLE to be broken.

Tested in 4.2.0.4 and 4.1.5.3, 100% reproductive.
              
Operating System: Ubuntu
Version: 4.2.0.4 release