I have a table that called search, with a field called ptype (blob,
subtype 2), and I am trying to select all records which have a blank
blob -- not null, but blank.

I have tried the following sql

SELECT * FROM "search"
WHERE "ptype" = '';

But this selects a lot of other records, which the ptype field is
most definatly not blank.

SELECT * FROM "search"
WHERE "ptype" IS NULL;

This one works normally, selecting null records, but does not select
those that are empty (not null).

Tried with FB1 and 1.5, on both Win32 and Linux.

Any ideas?

Andy