Need to Track Changes in one column

I have a table called rx_claims with columns epi, drugname, gpi. The table rx_claim is have historical saved data and I need to report if any changes in the gpi which is 16 digit number. The logic which I need is if the first 10 number of gpi changes from the historical data then report as new med and if 12 digits change then report as dose change with new and old column data.

for example : epi is 100 and drug name is ibrofine and gpi for this drug is 0123456789012300 ( historical data ) . Now we have a incoming record of 100 and drugname is still ibrofine but dosage change so it changes the gpi code to 0123456789000000 i.e the last 4 digits has changed so i want to show the resulted out as drugname : ibrofine and oldgpi is 0123456789012300 and new gpi is0123456789000000

you could use a query to compare the historical data with the current data

SELECT
  epi,
  drugname,
  gpi AS current_gpi,
  CASE
    WHEN SUBSTR(gpi, 1, 10) != SUBSTR(hist.gpi, 1, 10) THEN 'New Med'
    WHEN SUBSTR(gpi, 1, 10) = SUBSTR(hist.gpi, 1, 10) AND SUBSTR(gpi, 12, 5) != SUBSTR(hist.gpi, 12, 5) THEN CONCAT('Dose Change (Old GPI: ', hist.gpi, ')')
  END AS change_description
FROM
  rx_claims
LEFT JOIN
  (
    SELECT
      epi,
      gpi
    FROM
      rx_claims
    WHERE
      -- add condition to filter for historical data
      date < '2023-02-15'
  ) hist
ON
  rx_claims.epi = hist.epi

This query compares the current GPI value with the historical GPI value for each epi number. If the first 10 digits of the GPI value have changed, it reports the change as a "New Med". If only the 12th to 16th digits have changed, it reports the change as a "Dose Change" with the old GPI value included in the change description.