Question

I have a table in MYSQL on which I need to perform a select and then order it by a fairly complex logic. Here is an example of my logic:

if(column_a is not null && column_a > 0){
   var_a = column_a
else
   var_a = 1;

if(column_a is not null){
   var_b = column_b
else
   var_b = 0

if(column_c is not null){
   var_c = column_c
else
   var_c = column_d

ORDER BY (var_b*var_c)/var_a

So basically, I want to do something along the lines of SELECT * from mytable WHERE parameter = value ORDER BY variable_to_order_by . I would have to use some formula for variable_to_order_by, but I can’t find any way of doing it which would not involve eight separate CASE WHERE statements, and that seems extremely messy. Any other suggestions?

Thanks!

Answer 1

For a down and dirty way, you can use functions in an order by clause. In specific, you can use the if and ifnull functions. Therefore, you should be able to do something like this:

SELECT ...
ORDER BY IF(some_value IS NOT NULL AND some_value RLIKE '^[[:digit:]]+$', some_value, other_value)
       - (column_baz + IF(foo > bar, a, b))/(IFNULL(yet_another_value, 0) + IF(foo > bar, a, b))

(where the regular expression may have to be more complex if you want to include all reals instead of just integers, if you don’t want to include a string starting with 0, etc.)