Create class with dynamic width/interval

[#1]

Hi everyone, I have an imported field with some number, and I would like to create a class from this values. Let me explain:

I have this field:

ID_Cost     Cost

1               134

2               257

3               548

4               823

5               1004

and I would like to create something like this (I can't create it inline, since I need to import those values):

ID_cost_class      cost_class     class_name

1                         0-134               low price

2                         135-257           low-mid price

3                         258-548           mid price

4                         549-823           high-mid price

5                         824-                 high price

such to categorize some other elements by price

ID_item     price     price_class (this is the field to add)

1               374          mid price

2               194          low-mid price

3               834          high price

Please, can someone help me? Thankyou very much for any advice.