Question

I have a dataset with an ID and value. For each value I want to get its corresponding frequency in the dataset. What is the most efficient pure SQL query-based solution? (that is not using java etc…) Or would it be more efficient to use Java with SQL?

1. I am using Derby SQL

This is my previous solution for this problem

1. Get all distinct values in a new table and add a frequency column
2. Write Java code to iterate through all distinct values in this new table and run a counting query against the original dataset

I would really like to avoid the extra Java code…

All help is appreciated!

Answer 1

SELECT COUNT(DISTINCT value)
  FROM dataset