カラム名にテーブル名を含めるべきか否か考える https://twitter.com/neko314_/status/1579000770938433536?s=61&t=TGIhzWS_A0b4j3dWhxK50A

1.sql

WITH teams AS (
  SELECT 1 AS id
       , 'yancya-club' AS name)

, members AS (
  SELECT 1 AS id
       , 'yancya' AS name
       , 1 AS team_id)

SELECT *
  FROM members
         JOIN teams ON teams.id = team_id
;

--  id |  name  | team_id | id |    name
-- ----+--------+---------+----+-------------
--   1 | yancya |       1 |  1 | yancya-club

-- 確かに `id` とか `name` が複数あってダルそう

1.x.sql

WITH teams AS (
  SELECT 1 AS id
       , 'yancya-club' AS name)

, members AS (
  SELECT 1 AS id
       , 'yancya' AS name
       , 1 AS team_id)

SELECT id, name
  FROM members
         JOIN teams ON teams.id = team_id
;

-- ERROR:  column reference "id" is ambiguous
-- LINE 10: SELECT id, name

-- 辛い、でもまぁ、これは、それはそう、という気がする

2.sql

WITH teams AS (
  SELECT 1 AS team_id
       , 'yancya-club' AS team_name)

, members AS (
  SELECT 1 AS member_id
       , 'yancya' AS member_name
       , 1 AS member_team_id) -- ここがなぁ

SELECT member_id
     , member_name
     , member_team_id -- このなぁ
     , team_id
     , team_name
  FROM members
         JOIN teams ON teams.team_id = members.member_team_id
;

--  member_id | member_name | member_team_id | team_id |  team_name
-- -----------+-------------+----------------+---------+-------------
--          1 | yancya      |              1 |       1 | yancya-club

-- SELECT の部分はスッキリしている気はしますが、外部キーの名前に違和感が出てきますね……

3.sql

WITH teams AS (
  SELECT 1 AS id
       , 'yancya-club' AS name)

, members AS (
  SELECT 1 AS id
       , 'yancya' AS name
       , 1 AS team_id)

SELECT members.id AS member_id
     , members.name AS member_name
     , members.team_id AS member_team_id -- これは……
     , teams.id AS team_id
     , teams.name AS team_name
  FROM members
         JOIN teams ON teams.id = team_id
;

--  member_id | member_name | members_team_id | team_id |  team_name
-- -----------+-------------+-----------------+---------+-------------
--          1 | yancya      |               1 |       1 | yancya-club

-- 別名を付ければ済むわけですが、それが面倒というのも分かる
-- 別名も命名規約に従っていると微妙な別名を付けることになりかねない
-- JOIN のキーに使ったカラム名はテーブル名プレフィックスつけない方がいいのでは……

4.sql

WITH teams AS (
  SELECT 1 AS team_id
       , 'yancya-club' AS name)

, members AS (
  SELECT 1 AS id
       , 'yancya' AS name
       , 1 AS team_id)

SELECT members.id AS member_id
     , members.name AS member_name
     , team_id
     , teams.name AS team_name
  FROM members
         JOIN teams USING(team_id)
;

--  member_id | member_name | team_id |  team_name
-- -----------+-------------+---------+-------------
--          1 | yancya      |       1 | yancya-club

-- USING を使うと勝手にまとまってくれて嬉しい上にテーブル名で修飾しなくて済むようになる
-- そのために、サロゲートキー（主キー）だけは外部キーと同じ名前（テーブル名つきの名前）にしたらどうか思う事はある

99.sql

WITH team AS (
  SELECT 1 AS team_id
       , 'yancya-club' AS name)

, member AS (
  SELECT 1 AS id
       , 'yancya' AS name
       , 1 AS team_id)

SELECT member.id AS member_id
     , member.name AS member_name
     , team_id
     , team.name AS team_name
  FROM member
         JOIN team USING(team_id)
;


--  member_id | member_name | team_id |  team_name
-- -----------+-------------+---------+-------------
--          1 | yancya      |       1 | yancya-club

-- オフトピですが、テーブル名は単数形の方が良いのではと思うことがあります