Alter table set Identity column

问题

I have a sybase table ("Test") having the following columns:

MyIdentity numberic(9,0)
Name
User

The table is filled with lots of records. I want to alter MyIdentity column to be an identity.

There are currently no duplicate values for MyIdentity in the table. How can i alter the table and set MyIdentity as identity?

回答1:

Apparently you can't, something like

Create a new Table called test2 with the identity set up

Then

Set Identity_Insert Test2 On

Insert Test2 Select * From Test

Set Identity_Insert Test2 Off

Drop Test and Rename Test 2...

回答2:

At least on my version (Adaptive Server Enterprise/15.0.3) the following seems to do the trick (syntactic sugar omitted):

Add a new identity column:

alter table Test add newMyIdentity numeric(9,0) identity not null

Prepare for updates:

set identity_insert Test on
set identity_update Test on

Copy the existing ID (to be able to preserve foreign keys etc):

update Test set newMyIdentity=MyIdentity

Drop the old definition, rename the newly created column:

alter table Test drop MyIdentity
sp_rename "Test.newMyIdentity", MyIdentity

Clean up:

set identity_insert Test off
set identity_update Test off
sp_recompile Test

回答3:

Just use:

create index MyIdentity on Test

See http://manuals.sybase.com/onlinebooks/group-as/asg1250e/sqlug/@Generic__BookTextView/36137;pt=36137.

来源：https://stackoverflow.com/questions/9571249/alter-table-set-identity-column

标签

sybase