> Environment: Delphi 7, IBO 4.3Aa, FB 1.5 RC 7
>
> I have a Delphi routine to alter a table structure. In this
> particular instance I add an address field as a blob, copy data from
> 2 string fields into the blob field and then drop the string fields.
> My code looks something like this (simplified):

[snipped code samples...]

Ed,
In my experience, mixing DDL and DML statements doesn't always work as
they are supposed to. I have had to sometimes create the new field and copy
the data into it. Then, close the complete connection to the database and
reopen it before removing the old fields. I don't know if it's considered a
bug or just good practice to do this.

HTH

Woody (TMW)