When I first started using Oracle many years ago one of the most frustrating things was the amount of code and complexity required to parse/query CSV data (or any delimited data). As time passed I was able to leverage new features and techniques to help but they all had their issues. APEX 5.1 introduced a new API that may help simplify a lot of the headaches. The following example highlights this.

Suppose I had the following CSV data:

First Name, Last Name, Dept
Martin, DSouza, IT
John, Doe, Sales
Sally, Smith, Sales

The first thing to do is break each of the rows of text into rows of a query. This can be done using the new APEX 5.1 apex_string.split API

select *
from table(apex_string.split(:data,chr(10)))
;

-- Results in
COLUMN_VALUE                                
------------------------------
First Name, Last Name, Dept
Martin, DSouza, IT
john, doe, Sales
Sally, Smith, Sales

Where :data is the CSV data above. Note I'm using a Mac and the EOL character is a LF (chr(10)). Windows users use CR + LF (chr(13) || chr(10)). More info on this here

Now that each line of data is on it's own row we need to create columns. This can be done using regular expressions:

Update: originally I used regexp_substr(column_value, '[^,]+', 1, 1) as the regexp which caused issues with null values (ex abc,,def). I've since updated the code samples to handle nulls.

select
  rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 1), ',') fname,
  rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 2), ',') lname,
  rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 3), ',') dept
from table(apex_string.split(:data,chr(10)))
;

-- Results in
FNAME        LNAME       DEPT  
First Name   Last Name     Dept               
Martin         DSouza      IT                       
john         doe         Sales
Sally        Smith       Sales

To remove the header row change the query to:

select fname, lname, dept
from 
  (
    select 
      rownum rn,
      rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 1), ',') fname,
      rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 2), ',') lname,
      rtrim(regexp_substr(column_value, '([^,])*(,)?', 1, 3), ',') dept
    from table(apex_string.split(:data,chr(10)))
  )
where rn > 1