如何在 PostgreSQL 中加入这两个表？答案

【问题标题】：How to join these Two Tables in PostgreSQL?如何在 PostgreSQL 中加入这两个表？
【发布时间】：2016-01-07 06:16:06
【问题描述】：

如何加入这两个表我没有任何想法

CREATE TABLE entity_social_media (
entity_social_id integer NOT NULL,
entity_id integer NOT NULL,
entity_type character varying(50) NOT NULL,
sm_handle character varying(180),
sm_url character varying(180) NOT NULL,
sm_type_id integer NOT NULL,
created_at timestamp(6) without time zone DEFAULT now() NOT NULL,
updated_at timestamp(6) NULL,
social_media_id character varying(100)
);

CREATE TABLE persons (
person_id integer NOT NULL,
first_name character varying(50) NOT NULL,
last_name character varying(50) NOT NULL,
affiliation character varying(3) DEFAULT 'N/A'::character varying NOT NULL,
state_abbreviation character varying(2) DEFAULT 0 NOT NULL,
district character varying(5),
updated_at timestamp without time zone DEFAULT now() NOT NULL,
middle_name character varying(50),
nickname character varying(50),
status character varying(50) DEFAULT 'active'::character varying
);

如何加入这两个表

【问题讨论】：

你应该加入entity_id和person_id
它完全取决于数据。甚至没有列名。

标签： mysql postgresql hive

【解决方案1】：

从字段名称来看，这两个表中唯一可能的公共/相关字段是 entity_id 和 person_id
您可以按以下方式加入。

SELECT <entity_social_media.field1>,<entity_social_media.field2>,
    <persons.field1>,<persons.field2>
        FROM entity_social_media, persons
        WHERE entity_social_media.entity_id = persons.person_id;

【讨论】：