Question

I want to make sure I don’t have rounding issues when it comes to storing prices for products in a rails app.

What mysql datatype should I use, and what does it map to in rails?

I want decimal with 10 places for precision.

Answer 1

Sounds you want the :decimal column type. You can control the total number of digits and the number of decimal places with the :precision and :scale options:

add_column :mytable, :mycolumn, :decimal, :precision => 30, :scale => 10

A little more on data types in this documentation.