MySQL 使用 leftjoin 和 select

Question

i have two tables:

1. movie
id, userid, movie_id, status, score

2. movie_data
id, name_de, name_en, description, url

When i use this query:

SELECT * 
FROM `movie` LEFT JOIN 
      movie_data ON movie.movie_id = movie_data.id 
ORDER BY movie.id

When i enter this query, i get all fields, but also two times id. But i don't manage to show only the first "id" or rename the second id. i hope someone can help me :) Thanks for reading

Answer 1

You need to enumerate the columns in the SELECT clause and use aliases to disambiguate homonym columns:

SELECT
    m.id,
    m.user_id,
    m.movie_id,
    m.status,
    m.score,
    d.id data_id,   --> column alias
    d.name_de,
    d.name_en,
    d.description,
    d.url
FROM movie m 
LEFT JOIN movie_data d ON m.movie_id = d.id 
ORDER BY m.id

Answer 2

Explicitly list the columns you want. Don't use select * :

SELECT m.id, m.userid, m.movie_id, m.status, m.score,
       md.name_de, md.name_en, md.description, md.url
FROM `movie` m LEFT JOIN 
     movie_data md
     ON m.movie_id = md.id
ORDER BY m.id

Answer 3

You can also do, for example

SELECT 
    `movie`.*, -- select all fields from one table
     movie_data.id as movieId  -- and some fields of another table
FROM `movie` LEFT JOIN 
      movie_data ON movie.movie_id = movie_data.id 
ORDER BY movie.id

Answer 4

The query should be next:

SELECT 
    `movie`.`id`,
    `movie`.`userid`,
    `movie`.`movie_id`,
    `movie`.`status`,
    `movie`.`score`,
    `movie_data`.`name_de`,
    `movie_data`.`name_en`,
    `movie_data`.`description`,
    `movie_data`.`url`
FROM `movie` 
LEFT JOIN `movie_data` ON `movie`.`movie_id` = `movie_data`.`id` 
ORDER BY `movie`.`id`;

This way you can exactly select what you need