How to Dynamically Assign Set Names Based on Date Ranges in SQL?

Splitting Given String

To split the given dates represented by p_dates, use a regular expression to extract date ranges within brackets. For example:

SELECT string_to_array(p_dates, '[,]+') AS dates;

Splitting Given Sets

Use a similar regular expression to split the sets in p_sets using commas as the delimiter:

SELECT string_to_array(p_sets, '[,]+') AS sets;

Preparing Dynamic Case Statement

With the split dates and sets, construct a dynamic case statement using a loop:

DECLARE
  dates CHAR[],
  sets CHAR[];

BEGIN
  -- Get split dates and sets
  SELECT * INTO dates, sets FROM (
    SELECT string_to_array(p_dates, '[,]+') AS dates, string_to_array(p_sets, '[,]+') AS sets
  );

  -- Loop through each pair of date range and set
  FOR i IN 1..ARRAY_UPPER(sets) LOOP
    -- Construct CASE statement
    CASE WHEN given_dates BETWEEN split_part(dates[i], 'to', 1) AND split_part(dates[i], 'to', 2)
    THEN sets[i]
    END
  END CASE;
END;

This will generate a dynamic CASE statement that assigns set names based on the date ranges.

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