Updatable Only if Null property

This is where you specify whether the column's data can only be updated if empty (Null). If you set this to Yes, a value can never be changed once it is stored.

For example, if you set this value to Yes, you can only fill in an employee's department number if it has not yet been specified. If the employee changes department, the old record must be deleted before a new one can be entered.

NOTE: If you use the Definer to specify that a particular column is not updatable or updatable only if Null, you cannot then use the Updatable Only If Null property in the Windows Designer to change this setting for fields using that column. The Definer setting overrules the Windows Designer setting in this case. However, if you use the Definer to specify that a particular column IS updatable, you can then use the Windows Designer to specify that fields using this column are not updatable, or only updatable if Null.

Note also that if you specify that a column or a field based on that column is not updatable, using the Definer or the Windows Designer, it is not possible to change the background color of affected fields.