Question

I am constructing a query that pulls values out according to a set of ORDER BY instructions

SELECT * from values ORDER BY displayOrder, actualValue, field(key, 'A', 'B', 'C')

So this may return:

name        productType       displayOrder      actualValue       key
object_a    X                 1                 1.2               A
object_b    Z                 1                 1.2               C
object_c    Z                 1                 1.6               B
object_d    X                 1                 1.8               B

However, if productType = Z, I want to switch around the ORDER BY actualValue and field(key) to produce the following:

name        productType       displayOrder      actualValue       key
object_a    X                 1                 1.2               A
object_c    Z                 1                 1.6               B
object_b    Z                 1                 1.2               C
object_d    X                 1                 1.8               B

Is this possible in any way?

Answer 1

Try this:

SELECT *
FROM values
ORDER BY
    displayOrder
,   CASE WHEN productType <> Z THEN actualValue ELSE 0.0 END
,   CASE WHEN productType <> Z THEN field(key, 'A', 'B', 'C') ELSE 0 END
,   CASE WHEN productType = Z THEN field(key, 'A', 'B', 'C') ELSE 0 END
,   CASE WHEN productType = Z THEN actualValue ELSE 0.0 END

The idea is to put your order by expressions in both orders, but use only one of them for each row.