SQL - Calculate two fields in one Case - mysql

Question

I have a sql query that calculates a field as follows:
Select
Case When b.xField > 10
then 20
when b.xField > 48
then 10
else 0
end as field1
from (Select CASE WHEN numberChosen < 15
THEN 10
WHEN numberChosen > 15
THEN 48
END as xField
From secondTable) B
What I need is, when field1 is 10, then do some other calculations to save on another field.
Example something like:
then 20 AND field2 = yData - 26
so when the case is on 20, then have another field equal to yData - 26.
Can that be achieved using Cases in Sql ? Have two fields calculated in a single case?

Answer 1

I want to calculate two fields in one Case
You Can't Do That™.
You can put two case clauses in your query like this:
Select
Case When xField > 10
then 20
when xField > 48
then 10
else 0
end as field1,
Case When xField > 10
then ydata - 26
else 0
end as field2
from myData
Or you can generate the extra field value in a wrapper query if it is really hard to compute field2
SELECT field1, CASE WHEN field1 > 10 THEN ydata -20 ELSE 0 END field2
FROM (
Select
ydata,
Case When xField > 10
then 20
when xField > 48
then 10
else 0
end as field1
from myData
) subquery

Answer 2

You can use the base logic that is deciding when field1 = 10 (ie. xField > 48) in the second case:
SELECT CASE WHEN xField > 48
THEN 10
WHEN xField > 10
THEN 20
ELSE 0
END as field1,
CASE WHEN xField > 48
THEN yData - 26
END as field2
FROM (SELECT CASE WHEN numberChosen < 15
THEN 10
WHEN numberChosen > 15
THEN 48
END as xField,
yData
FROM secondTable) B
I changed the order of your case because putting the > 10 condition before the > 48 condition will never let the > 48 be hit.