Disclaimer: This is not a database administration or design question. I did not design this database and I do not have rights to change it.
I have a database in which many fields are compound. For example, a single column is used for acre usage for a district. Many districts have one primary crop and the value is a single number, such as 14. Some have two primary crops and it has two numbers separated by a comma like "14,8". Some have three, four, or even five primary crops resulting in a compound value like "14,8,7,4,3".
I am pulling data out of this database for analytical research. Right now, I am pulling columns like that into R, splitting them into 5 values (padding nulls if there aren't 5 values), and performing work on the values. I want to do it in the database itself. I want to split the value on the comma, perform an operation on the resulting values, and then concatenate the result of the operation back into the original column format.
Example, I have a column that is in acres. I want it in square meters. So, I want to take "14,8", temporarily turn it into 14 and 8, multiply each of those by 4046.86, and get "56656.04,32374.88" as my result. What I am currently doing is using regexp_replace. I start with all rows where "acres REGEXP '^[0-9.]+,[0-9.]+,[0-9.]+,[0-9.]+$'" for the where clause. That gives me rows with 5 numbers in the field. Then, I can do the first number with "cast(regexp_replace(acres,',.*%','') as float) * 4046.86". I can do each of the 5 using a different regexp_replace. I can concatenate those values back together. Then, I run a query for those with 4 numbers, then 3, then 2, and finally the single number rows.
Is this possible as a single query?