CxCufES8

1create table versions (
2  key           text primary key,
3  version       text );
4
5/* ### TAINT not sure whether there may be race conditions with this upsert trigger */
6create function on_before_insert_versions() returns trigger language plpgsql volatile as $$ begin
7  if exists ( select 1 from versions where key = new.key ) then
8    update versions set version = new.version where key = new.key;
9    return null;
10    end if;
11  return new;
12  end; $$;
13
14create trigger on_before_insert_versions
15  before insert on versions for each row execute procedure on_before_insert_versions();
16
17insert into versions values
18  ( 'server', '3.0.3' ),
19  ( 'api',    '2' );
20
21insert into versions values
22  ( 'api',    '3' );
23
24select * from versions;
25
26  key   | version 
27--------+---------
28 server | 3.0.3
29 api    | 3