How to define a custom ORDER BY order in mySQL

Question

In MySQL how do I define a custom sorting order.

To try to explain what I want consider this table:

ID  Language    Text
0   ENU         a
0   JPN           


        

Answer 1

You have a couple of options offhand, the first is to change Language to be ENUM (assuming this is possible, and you only expect a few variations)

If you specify it as ENUM('ENU','JPN','DAN') then ORDER Language ASC will order in the order you specify.

The second will involve a case somewhere, i.e.

SELECT * FROM table
ORDER BY CASE Language
    WHEN 'ENU' THEN 3
    WHEN 'JPN' THEN 2
    WHEN 'DAN' THEN 1
    ELSE 0
END DESC, ID ASC

Performance-wise the ENUM method will return faster results, but be more hassle if you need to add more languages. A third option would be to add a normalisation table for the Languages however that may be overkill in this instance.

Answer 2

MySQL has a handy function called FIELD() which is excellent for tasks like this.

ORDER BY FIELD(Language,'ENU','JPN','DAN'), ID

Note however, that

1. It makes your SQL less portable, as other DBMSs might not have such function

2. When your list of languages (or other values to sort by) gets much longer, it's better to have a separate table with sortorder column for them, and join it to your queries for ordering.

Answer 3

If those are the only three values, then you can use a CASE expression:

ORDER BY `ID`,
         CASE `Language`
         WHEN 'ENU' THEN 1
         WHEN 'JPN' THEN 2
         WHEN 'DAN' THEN 3
         END

(If there could be other values, then you may want to add some extra logic to keep the ordering consistent; for example, you might add ELSE 4 to that CASE expression, and then order by Language itself as the third ordering criterion:

ORDER BY `ID`,
         CASE `Language`
         WHEN 'ENU' THEN 1
         WHEN 'JPN' THEN 2
         WHEN 'DAN' THEN 3
         ELSE 4
         END,
         `Language`

)

Answer 4

For Yii2 framework we cab achieve by following way

Project::find()
->orderBy([new Expression('FIELD(pid_is_t_m,2,0,1)'),'task_last_work'=> SORT_ASC])
->all();