<分区>
我有两个数组:函数中的 foo_array text[]、bar_array text[]。 它们每个都包含字符串，这些字符串将使用“string_to_array”函数拆分为数组元素并将类型转换为 bigint。
我想在表中返回这些数组(out1 bigint，out2 bigint)。
例如，foo_array 和 bar_array 各包含 10 个元素，我希望该函数返回包含这些元素的 10 行。 我只能产生 20 个元素的输出，但并不真正理解。
CREATE OR REPLACE FUNCTION ___two_unnests()
RETURNS TABLE(out1 bigint, out2 bigint) AS $$
DECLARE
foo_array text[];
bar_array text[];
foo1 text := array_to_string(ARRAY[1, 2, 3, 4, 5], ',');
foo2 text := array_to_string(ARRAY[11, 22, 33, 44, 55], ',');
bar1 text := array_to_string(ARRAY[6, 7, 8, 9, 10], ',');
bar2 text := array_to_string(ARRAY[66, 77, 88, 99, 1010], ',');
BEGIN
foo_array := (SELECT foo_array || foo1 || foo2);
bar_array := (SELECT bar_array || bar1 || bar2);
RAISE NOTICE 'foo_array: %', foo_array;
RAISE NOTICE 'bar_array: %', bar_array;
RETURN QUERY
SELECT
unnest(string_to_array(foo, ',')::bigint[]),
unnest(string_to_array(bar, ',')::bigint[])
FROM
unnest(foo_array) as foo,
unnest(bar_array) as bar;
END;
$$ LANGUAGE plpgsql;
SELECT * FROM ___two_unnests();
函数的实际输出。
out1 | out2
-----+-----
1 | 6
2 | 7
3 | 8
4 | 9
5 | 10
1 | 11
2 | 22
3 | 33
4 | 44
5 | 55
11 | 6
22 | 7
33 | 8
44 | 9
55 | 10
11 | 11
22 | 22
33 | 33
44 | 44
55 | 55
我想要的输出:
out1 | out2
-----+-----
1 | 6
2 | 7
3 | 8
4 | 9
5 | 10
11 | 66
22 | 77
33 | 88
44 | 99
55 | 1010
解决方案使用 sticky-bit's建议
CREATE OR REPLACE FUNCTION ___two_unnests() RETURNS TABLE(out1 bigint, out2 bigint) AS $$
DECLARE
foo_array text[];
bar_array text[];
foo_slice text;
foo_text text := '';
foo_firstiter boolean := true;
bar_slice text;
bar_text text := '';
bar_firstiter boolean := true;
out1_array bigint[];
out2_array bigint[];
foo1 text := array_to_string(ARRAY[1, 2, 3, 4, 5], ',');
foo2 text := array_to_string(ARRAY[11, 22, 33, 44, 55], ',');
bar1 text := array_to_string(ARRAY[6, 7, 8, 9, 10], ',');
bar2 text := array_to_string(ARRAY[66, 77, 88, 99, 1010], ',');
BEGIN
foo_array := (SELECT foo_array || foo1 || foo2);
bar_array := (SELECT bar_array || bar1 || bar2);
RAISE NOTICE 'foo_array: %', foo_array;
RAISE NOTICE 'bar_array: %', bar_array;
FOREACH foo_slice IN ARRAY foo_array LOOP
IF foo_firstiter = true THEN
foo_text := foo_text || foo_slice;
foo_firstiter := false;
ELSE
foo_text := foo_text || ',' || foo_slice;
END IF;
END LOOP;
FOREACH bar_slice IN ARRAY bar_array LOOP
IF bar_firstiter = true THEN
bar_text := bar_text || bar_slice;
bar_firstiter := false;
ELSE
bar_text := bar_text || ',' || bar_slice;
END IF;
END LOOP;
out1_array := (SELECT string_to_array(foo_text, ',')::bigint[]);
out2_array := (SELECT string_to_array(bar_text, ',')::bigint[]);
RAISE NOTICE 'out1_array: %', out1_array;
RAISE NOTICE 'out2_array: %', out2_array;
RETURN QUERY SELECT un1.val::bigint,
un2.val::bigint
FROM unnest(out1_array) WITH ORDINALITY un1 (val, ord)
FULL JOIN unnest(out2_array) WITH ORDINALITY un2 (val, ord)
ON un2.ord = un1.ord;
END;
$$ LANGUAGE plpgsql;
SELECT * FROM ___two_unnests();