sql - Postgres Inner Join Select 查询返回错误 : column does not exist

Question

我一直在阅读文档，但找不到我在这里做错了什么。

我正在执行这个查询:

SELECT *
FROM "parts"
INNER JOIN "categories" ON "categories"."id" = "parts"."category_id"
WHERE "categories"."name" = "cars"

我收到这个错误:

ERROR:  column "cars" does not exist
LINE 3: WHERE (categories.name = "cars")
                                 ^
********** Error **********

ERROR: column "cars" does not exist
SQL state: 42703
Character: 122

分类表:

CREATE TABLE categories
(
  id serial NOT NULL,
  name character varying(255),
  CONSTRAINT categories_pkey PRIMARY KEY (id)
)

零件表:

CREATE TABLE parts
(
  id serial NOT NULL,
  category_id integer,
  CONSTRAINT parts_pkey PRIMARY KEY (id)
)

如有任何帮助，我们将不胜感激。

Answer 1

您应该对字符串常量使用单引号:

SELECT *
FROM "parts"
INNER JOIN "categories" ON "categories"."id" = "parts"."category_id"
WHERE "categories"."name" = 'cars'

double 表示数据库对象。(字段、表等)

(否则它们不是必需的，仅用于额外的，例如名称中的空格等)