I encountered strange behavior droping a column definition with default value.

The environment is Ubuntu 16.04 LTS 64 bits, Firebird version LI-V2.5.6.27020 (Firebird 2.5 SuperClassic)

I'll try to explain with an example. The statement sequence is:

1. Create the table

CREATE TABLE "SCHEMA_AUTHOR" ("ID" integer NOT NULL PRIMARY KEY, "NAME" varchar(255) NOT NULL, "HEIGHT" integer CHECK ("HEIGHT" >= 0))

2. Popultate with some data

3. Alter the table

ALTER TABLE "SCHEMA_AUTHOR" ADD "SURNAME" varchar(15) DEFAULT 'surname default' NOT NULL

After step 3, I have a record with a new column with 'surname default' value into SURNAME field.

4. Drop default definition

ALTER TABLE "SCHEMA_AUTHOR" ALTER COLUMN "SURNAME" DROP DEFAULT

After step 4, the SURNAME field value is setting to empty string ('')

Is that the correct behavior ?

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