复合类型数组的正确语法

Question

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

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

INSERT INTO pencils(pencils_) VALUES('{("blue",5),("red",2)}');

这不起作用并给出错误：

Malformed array literal.

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

I want to add this composite array without using ARRAY

您可以使用：

INSERT INTO pencils(pencils_) 
VALUES('{"(\"blue\",5)","(\"red\",2)"}');

db<>fiddle demo

Row type

Remember that what you write in an SQL command will first be interpreted as a string literal, and then as a composite. This doubles the number of backslashes you need (assuming escape string syntax is used).

The string-literal processor removes one level of backslashes.

The ROW constructor syntax is usually easier to work with than the composite-literal syntax when writing composite values in SQL commands. In ROW, individual field values are written the same way they would be written when not members of a composite.

Answer 2

目前的建议不是最佳的。有一个更简单的解决方案和实际适用的解释。
如有疑问，请 Postgres 向您展示:

CREATE TEMP TABLE pencil_count (  -- table also registers row type
  pencil_color varchar(30)
, count integer
);

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

插入 2 个基本行：

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

查看基本行类型的语法：

SELECT p::text AS p_row FROM pencil_count p;

  p_row
----------
 (red,1)
 (blue,2)

查看行数组的语法：

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

       p_row_arr
------------------------
 {"(red,1)","(blue,2)"}

您只需要用双引号将每一行文字括起来 - 这只需要禁用每个行类型中逗号的特殊含义。
如果没有额外的特殊字符，额外的（转义的）双引号将是多余的噪音。

None 这与 ~~转义字符串语法~~ 有任何关系，自 Postgres 以来，它已被默认关闭 9.1.您必须通过前缀 E 来显式声明转义字符串语法，例如 E'string\n'。但是没有充分的理由这样做。

db<>fiddle here
_旧sqlfiddle

更多解释的相关答案：

Insert text with single quotes in PostgreSQL
How to pass custom type array to Postgres function
PL/pgSQL Array of Rows

复合类型数组的正确语法

Correct syntax for array of composite type

arrays

postgresql

postgresql-9.4