How to Preserve the Order of Values in a MySQL `IN` Query?

Preserving Sequence in MySQL "IN" Queries

In MySQL, the "IN" operator selects records that match any value in a provided list. By default, the results are returned in the order defined by the database's sorting algorithm, which may not always align with the sequence specified in the query.

Let's consider the following example:

SELECT * FROM foo f WHERE f.id IN (2, 3, 1);

This query aims to retrieve records with IDs 2, 3, and 1. However, the results are typically ordered by ID ascending:

+----+--------+
| id | name   |
+----+--------+
|  1 | first  |
|  2 | second |
|  3 | third  |
+----+--------+

To maintain the sequence specified in the query, we need to explicitly order the results. The ORDER BY FIELD() function can achieve this.

SELECT * FROM foo f WHERE f.id IN (2, 3, 1)
ORDER BY FIELD(f.id, 2, 3, 1);

The FIELD() function takes a value as the first argument and a list of values as the remaining arguments. It returns the position of the value in the list. For example, FIELD(2, 2, 3, 1) returns 1 because 2 is the first value in the list.

By ordering the results by FIELD(f.id, 2, 3, 1), we instruct MySQL to first sort the records by their first value (2), then by their second value (3), and finally by their third value (1). This sequence ensures that the results are returned in the same order as they appear in the query.

+----+--------+
| id | name   |
+----+--------+
|  2 | second |
|  3 | third  |
|  1 | first  |
+----+--------+

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