David Bowman wrote:
I am trying to create a table in Base. After saving the table I can not
change a field name or type. How can I make changes?
Hello David,
Simply open the table definition for editing. In the Table section of
the Base window select the table item and select 'Edit>Edit' this opens
the table properties editor. In this window just change the name and
save the file. Now - are there any times when you can not do this?
Yes. If the field is part of an index, used in a View, or is "referred
to" in a foreign key relationship. Then you can not change the name,
until you have dropped ( deleted ) those other objects. ( kind of makes
sense as otherwise those other objects would be referring to a field
that no longer exists )
Changing data types is a little different.
If the field is holding data then your ability to change type depends on
both the current type and the type you want to change to.
Generally speaking a like type, that is larger, is allowed.
So a SmallInt can become an Ingeger or BigInt. A Varchar(50) can become
a Varchar(100).
Making a type into a smaller type is usually not allowed, BigInt can not
become SmallInt in other words.
Changing from a CHAR to VARCHAR is not allowed.
Changing from a Real, Float or Decimal to an Integer type is not
allowed. ( I don't remember for the other direction, but I think it is not )
The user documentation for the HSQLdb database engine, that used in a
default Base file, has a section on this subject and can be found at
http://hsqldb.org
ALSO - if you make a change and the application warns you that it must
drop the column and make a new one - understand that this will delete
any data in that column ( field ), the data will not be moved to the new
column and if you say OK to that warning there will be no way to recover
the deleted data. To save the data you must do so before you make the
change. For instance, by ADDING the new column, then using INSERT
statements to transfer the data from the old column to the new and
finally dropping the old. ( you can also do this using the Copy Table
Wizard ).
I HTH - but it may raise more questions then offer answers I'm afraid.
Let me know if that is the case.
Drew
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