> On 4 Nov 2021, at 14:26, David G. Johnston <david.g.johns...@gmail.com> wrote: > > On Thursday, November 4, 2021, Daniel Gustafsson <dan...@yesql.se > <mailto:dan...@yesql.se>> wrote: > > On 22 Mar 2021, at 20:40, David Oksman <oksman....@gmail.com > > <mailto:oksman....@gmail.com>> wrote: > > > > Added the ability to specify IF EXISTS when renaming a column of an object > > (table, view, etc.). > > For example: ALTER TABLE distributors RENAME COLUMN IF EXISTS address TO > > city; > > If the column does not exist, a notice is issued instead of throwing an > > error. > > What is the intended use-case for RENAME COLUMN IF EXISTS? I'm struggling to > see when that would be helpful to users but I might not be imaginative enough. > > Same reasoning as for all the other if exists we have, idempotence. Being > able to run the command on an object that is already in the desired state > without provoking an error.
If the object is known to be in the desired state, there is no need to use IF EXISTS. Personally I think IF EXISTS commands are useful when they provide a transition to a known end state, but in this case it's an unknown end state. -- Daniel Gustafsson https://vmware.com/
