如何创建对数组中所有值的唯一性的约束,如：
CREATE TABLE mytable
(
interface integer[2],CONSTRAINT link_check UNIQUE (sort(interface))
)
我的排序功能
create or replace function sort(anyarray) returns anyarray as $$ select array(select $1[i] from generate_series(array_lower($1,1),array_upper($1,1)) g(i) order by 1) $$language sql strict immutable;
我需要这样的价值{10,22}和{22,10}被认为是一样的,并在独特的约束下检查
我不认为你可以使用一个
unique constraint的功能,但你可以使用
unique index.所以给出一个这样的排序功能：
create function sort_array(integer[]) returns integer[] as $$
select array_agg(n) from (select n from unnest($1) as t(n) order by n) as a;
$$language sql immutable;
那么你可以这样做：
create table mytable (
interface integer[2]
);
create unique index mytable_uniq on mytable (sort_array(interface));
然后发生以下情况：
=> insert into mytable (interface) values (array[11,23]);
INSERT 0 1
=> insert into mytable (interface) values (array[11,23]);
ERROR: duplicate key value violates unique constraint "mytable_uniq"
DETAIL: Key (sort_array(interface))=({11,23}) already exists.
=> insert into mytable (interface) values (array[23,11]);
ERROR: duplicate key value violates unique constraint "mytable_uniq"
DETAIL: Key (sort_array(interface))=({11,23}) already exists.
=> insert into mytable (interface) values (array[42,11]);
INSERT 0 1