如何将新项目添加到 PostgreSQL 中的字符变化数组

Question

I am trying to start an plpgsql function to store in a variable several elements of an array of type character varying, I would like to know what is the syntax to store element by element.

Answer 1

If I understood your question correctly, you want to append to an array using a loop in plpgsql .

Below are a couple strategies for doing that:

create or replace function add_new_item_to_array() returns void as $$
    DECLARE
        tmp_elem varchar;
        elem1 varchar;
        elem2 varchar;
        elem3 varchar;
        varchar_array varchar[];
    BEGIN
        elem1 := 'elem1';
        elem2 := 'elem2';
        elem3 := 'elem3';
        -- option 1: literal array construction, if you know all the elements in advance
        varchar_array := array[elem1, elem2, elem3];

        -- option 2: array construction with a loop using sql query
        varchar_array := array[]::varchar[];
        FOR tmp_elem IN SELECT elem1 UNION SELECT elem2 UNION SELECT elem3 LOOP
            varchar_array := varchar_array || tmp_elem;
            -- alternative syntax:
--             varchar_array := array_append(varchar_array, tmp_elem);

        END LOOP;
        RAISE NOTICE 'varchar_array: %', varchar_array;
    END

$$ language plpgsql;