Question

Considering this MySQL query:

SELECT
  someColumns
FROM
  someTable
WHERE
  someColumn IN ( value1, value2, value3 )

… how can I guarantee that the rowset comes out ordered in the exact order of the values given to the IN () clause? I presume this is not guaranteed without giving it an ORDER BY clause, is it?

PS.:
The values to the IN () clause will be an array of arbitrary data passed to the query by PHP (utilizing Zend Framework’s select statement) in the following manner:

->where( 'someColumn in (?)', $theArrayWithValues );

Answer 1

Use a CASE statement in the ORDER BY:

ORDER BY CASE someColumn
           WHEN value1 THEN 1
           WHEN value2 THEN 2
           WHEN value3 THEN 3
         END ASC

Assign the arbitrary values as you like. I don’t normally include ASC in ORDER BY because it is implied if not defined, but I wanted to be explicit in case you want in DESC order.