--数组: SELECT (ARRAY['{101, 111, 121}', '{201, 211, 221}'])[1]::text[]; SELECT (ARRAY['{101, 111, 121}', '{201, 211, 221}'])::text[];
SELECT (ARRAY['{101, 111, 121}', '{201, 211, 221}'])[1]::text[]; SELECT (ARRAY['{101, 111, 121}'::int[], '{201, 211, 221}'])::int[]; SELECT (ARRAY['{101, 111, 121}'::int[], '{201, 211, 221}'])[1][1]; SELECT (ARRAY['{{101, 111, 121},{201, 211, 221}}'])[1]; SELECT (ARRAY['{{101, 111, 121},{201, 211, 221}}'])[1]::int[];