Databases
StackOverflow2013
Postsdbo
POMySQL: How to combine a column referenced multiple times from another table and assign proper aliases?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POMySQL: How to combine a column referenced multiple times from another table and assign proper aliases?
    primarykey
    data
    text
    <p>The question I've got here may look silly, but it drives me a bit crazy, as I can't get how the MySQL join works.</p> <p>I have 2 tables:</p> <pre><code>user; +--------------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------------+--------------+------+-----+---------+-------+ | id | int(11) | NO | PRI | NULL | | | name | varchar(128) | NO | | NULL | | +--------------------+--------------+------+-----+---------+-------+ game; +--------------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------------+--------------+------+-----+---------+-------+ | id | int(11) | NO | PRI | NULL | | | source_id* | int(11) | NO | | NULL | | | target_id* | int(11) | NO | | NULL | | +--------------------+--------------+------+-----+---------+-------+ </code></pre> <p><code>game.source_id</code> and <code>game.target_id</code> are constraints that reference the <code>user.id</code>.</p> <p>Now I want to select everything from <code>game</code> table and I want to include in the result names of 2 users, since <code>game</code> has 2 users. And I want those columns to be named as <code>target_name</code> and <code>source_name</code> specifically.</p> <p><strong>Tried this query</strong>:</p> <pre><code>SELECT g.id, u.name FROM game g RIGHT JOIN user u ON u.id = g.source_id OR u.id = g.target_id WHERE g.source_id = 1 OR g.target_id = 1 ; </code></pre> <p>But as you may have noticed, I don't alias <code>u.name</code> as <code>target_name</code> or <code>source_name</code> because I don't know how to do that and end result looks like this:</p> <pre><code>+----+------+ | id | name | +----+------+ | 1 | bo | | 1 | al | | 2 | jo | | 2 | jay | +----+------+ </code></pre> <p>As you can see, there's a <code>game</code> appearing multiple times in the result.</p> <p><strong>Expected result:</strong></p> <pre><code>+----+-------------+-------------+ | id | target_name | source_name | +----+-------------+-------------+ | 1 | bo | al | | 2 | jo | jay | +----+-------------+-------------+ </code></pre> <p>Thanks in advance.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USAleksandr Makov
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. This table or related slice is empty.
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload