不使用 ARRAY[] 的嵌套复合类型数组的语法

Question

CREATE TYPE pencil_count AS(
    pencil_color varchar(30),
    count integer
);

CREATE TYPE pencil_count_with_date(
date_ date,
pencil_count pencil_count[]
);

CREATE TABLE pencils(id serial, pencils_ pencil_count_with_date[]);

INSERT INTO pencils(pencils_) 
VALUES('{"(\"2016-03-13\",{"(\"blue\",1)","(\"red\",2)"})"}');

如果我想在不使用 ARRAY[...] 的情况下添加此复合数组，正确的语法是什么？

Answer 1

添加新的嵌套级别时，使用文字字符串的可读性会降低：

CREATE TYPE pencil_count AS(pencil_color varchar(30)
       ,"count" int);

CREATE TYPE pencil_count_with_date AS(date_ date
                                     ,pencil_count pencil_count[]);

CREATE TABLE pencils(id serial, pencils_ pencil_count_with_date[]);

INSERT INTO pencils(pencils_) 
VALUES('{"(
               \"2016-03-13\",
               \"{
                   \"\"(Blue,5)\"\",
                   \"\"(Red,2)\"\"
               }\"
          )"}');   


SELECT pencils_[1].pencil_count[1].pencil_color
FROM pencils;

SqlFiddleDemo

备注：

您需要根据嵌套级别用 " 转义 \ 来引用每个级别。
这种模式看起来像是试图将 OO 世界引入数据库。与规范化版本相比，它可能更难维护且速度更慢。 Related question.
如果需要，您可以用 $$ 引用字符串文字。
使用 ARRAY 和 ROW 可以更容易地找出每个级别的开始和结束位置。

Answer 2

再次询问 Postgres。扩展的程序：

CREATE TEMP TABLE pencil_count (
  pencil_color varchar(30)
, count integer
);

CREATE TABLE pencil_count_with_date (
 date_ date,
 pencil_count pencil_count[]
);

CREATE TABLE pencils (
  id serial
, pencils_ pencil_count_with_date[]
);

向 Postgres 询问每个嵌套级别：

INSERT INTO pencil_count VALUES ('red' , 1), ('blue', 2);

SELECT ARRAY(SELECT p FROM pencil_count p)::text AS p_row_arr;

-- with result from above:
INSERT INTO pencil_count_with_date(date_, pencil_count)
VALUES ('2016-04-14', '{"(red,1)","(blue,2)"}')
     , ('2016-04-14', '{"(red,3)","(blue,4)"}');

SELECT ARRAY(SELECT p FROM pencil_count_with_date p)::text AS p2_row_arr;

-- with result from above:
INSERT INTO pencils(pencils_)
VALUES
  ('{"(2016-04-14,\"{\"\"(red,1)\"\",\"\"(blue,2)\"\"}\")"
    ,"(2016-04-15,\"{\"\"(red,3)\"\",\"\"(blue,4)\"\"}\")"}');

SELECT id, pencils_::text FROM pencils;

结果：

id | pencils_
---+-------------------------------------------------------
1  | {"(2016-04-14,\"{\"\"(red,1)\"\",\"\"(blue,2)\"\"}\")"
     ,"(2016-04-15,\"{\"\"(red,3)\"\",\"\"(blue,4)\"\"}\")"}

SQL Fiddle.

到目前为止，我完全同意以下建议：多层嵌套行类型通常很复杂且效率低下。考虑归一化。

更多内容在我对你之前问题的回答中：

不使用 ARRAY[] 的嵌套复合类型数组的语法

Syntax for array of nested composite type without using ARRAY[]

sql

arrays

postgresql

postgresql-9.4