[DERBY-4011] ALTER COLUMN is only allowed to change default value of some types of generated columns

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Duplicate
• Affects Version/s: 10.5.1.1
• Component/s: SQL
• Labels: derby_triage10_10
• Urgency: Normal
• Assignee: Unassigned
• Reporter: Knut Anders Hatlen
• Created: 09/Jan/09 09:22
• Updated: 17/Sep/14 11:59
• Resolved: 17/Sep/14 11:59

Description

ALTER TABLE ... ALTER COLUMN is allowed to change the default of columns that are GENERATED ALWAYS AS IDENTITY, but it's not allowed to change the default of columns that are GENERATED ALWAYS AS (expression). It would be good if it had the same behaviour for all generated columns.

ij> create table t1(x int generated always as (-1));
0 rows inserted/updated/deleted
ij> alter table t1 alter column x default 22;
ERROR 42XA7: 'X' is a generated column. You cannot change its default value.
ij> create table t2(x int generated always as identity);
0 rows inserted/updated/deleted
ij> alter table t2 alter column x default 22;
0 rows inserted/updated/deleted
ij> insert into t2 values default;
1 row inserted/updated/deleted
ij> select * from t2;
X
-----------
22

1 row selected

Issue Links

• duplicates: DERBY-6545 Should not be able to add a default to an identity column