aku ade existing table (TableA) yang dah ada sangat banyak data
aku nak add 1 column baru (ColumnABC) dan aku nak column ni unique
aku execute query ni success
[CODE]
use DatabaseA alter table (TableA) add ColumnABC varchar(25)
[/CODE]
lpas tu aku execute ni plak
[CODE]
use DatabaseA
alter table (TableA) ADD CONSTRAINT ColumnABC_unique UNIQUE NONCLUSTERED(ColumnABC)
[/CODE]
then aku dapat error ni
[color=#ff0000]Msg 1505, Level 16, State 1, Line 1
The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name 'dbo.TableA' and the index name 'ColumnABC_unique '. The duplicate key value is (<NULL>).
Msg 1750, Level 16, State 0, Line 1
Could not create constraint. See previous errors.
The statement has been terminated.[/color]
kalau aku try
[CODE]
use DatabaseA
ALTER TABLE TableA ADD ColumnABC varchar(25) NULL UNIQUE
[/CODE]
pun kluar error yang sama
soalannya: adakah sebab data2 kat column yang baru create tu akan jadi null so sbb tu ak x boleh set dier jadi unique?