Greetings,
I am using PostgreSQL 10.10. I am having trouble incrementing a column for reasons I can't see. It's probably some basic SQL thing. Your help is appreciated.
create table my_table (
listid char(36) not null,
seq smallint not null,
item varchar(4096),
primary key (listid, seq)
);
insert into my_table (listid, seq) values ('abc', 1);
insert into my_table (listid, seq) values ('abc', 2);
-- the following works some of the time
update my_table set seq=seq+1;
-- the following doe not work for reasons I do not know
update my_table set seq=seq+1 where listid='abc';
What I get is a duplicate primary key. I wouldn't think I'd get that because I'd think the whole thing is done in a transaction so that duplicate checks wouldn't be done till the end (essentially).
Is there a clean way to do this?
Thanks!
Blake McBride