ORDER BY with added calculation

Databases
1

SELECT field1 FROM table1 ORDER BY field2, field3

However I need to add something in so it also orders by a value that is returned from a calculation:

SELECT field1 FROM table1 ORDER BY field2, (if field 4==“” and field 5==1 then order these records in order), field3

So they are ordered by field2, then the calculation, then field3

2

SELECT field1 FROM table1 ORDER BY field2, CASE WHEN @a=1 Then UserName Else FirstName END
, field3

@a is an example variable here.

3

what if field4 isn’t empty, or field 5 isn’t 1? what then?

4

Thanks webcosmo, I managed to work it out from this.

SELECT field1 FROM table1 ORDER BY field2, CASE WHEN field4='“” && field5=1 THEN 1 ELSE 0 END, field3