如何使用IN命令保留SQL查询的顺序

Question

SELECT * FROM tblItems
WHERE itemId IN (9,1,4)

Returns in the order that SQL finds them in (which happens to be 1, 4, 9) however, I want them returned in the order that I specified in the array.

I know I could reorder them after in my native language (obj c), but is there a neat way to do this in SQL?

Somthing like this would be great:

ORDER BY itemId (9,1,4) --    <-- this dosn't work :)

Answer 1

Probably the best way to do this is create a table of item IDs, which also includes a rank order. Then you can join and sort by the rank order.

Create a table like this:

 itemID rank
 9      1
 1      2
 4      3

Then your query would look like this:

select tblItems.* from tblItems
    inner join items_to_get on
        items_to_get.itemID = tblItems.itemID
    order by rank

Answer 2

Use a CASE expression to map the ID values to an increasing sequence:

... ORDER BY CASE itemId
             WHEN 9 THEN 1
             WHEN 1 THEN 2
             ELSE        3
             END

Answer 3

You can add a case construct to your select clause.

select case when itemid = 9 then 1
when itemid = 1 then 2 else 3 end sortfield
etc
order by sortfield

Answer 4

I had the same task once in a mysql environment.

I ended up using

ORDER BY FIND_IN_SET(itemID, '9,1,4')

this is working for me since then. I hope it also works for sqlite

Answer 5

You could create a procedure to order the data in SQL, but that would be much more complicated than its native language counterpart.

There's no "neat way" to resort the data like that in SQL -- the WHERE clause of a SELECT simply says "if these criteria are matched, include the row"; it's not (and it cannot be) an ordering criterion.