AntonyRayan it is possible , just create a new field in the table with the type you like , a batch to copy data appropriately from the old field to the new , and delete the old field (after that you could even rename the new field to have the name the old had)
As jkon says. You could run a simple query to convert it too. Why 1500 records should nake any diffrrence. Did you assume you.d have to do it manually?
I have been working with www.essayhelpdeal.co.uk non-SQL databases for more than 20 years. I chose to update my aptitude set and get a MCDBA cert (Microsoft Certified Data Base Analyst), and it took any longer than I suspected to finish the Database Design test. For your situation, I'd propose that you utilize Microsoft Access as the back end. You can manufacture reports and detach records without learning SQL (altho you can see the SQL they create as you go). At that point it turns into a matter of discovering how to trigger Access activities from the web. That is not my range of aptitude.
SELECT * FROM `TABLENAME` ODER BY date_format(str_to_date(`TIME_COLUMN`, '%r'), '%T') ASC;
This will convert the string to a timestamp that MySQL can parse, then use %T to get the order in the 24H format. But, as suggested, it's better to convert the existing rows into the 24H format and then always save in that format, to avoid extra processing. So you could run an update query, just like above:
UPDATE `TABLENAME` SET `TIME_COLUM` = date_format(str_to_date(`TIME_COLUMN`, '%r'), '%T');
Replace TABLENAME and TIME_COLUMN with yours and remember to test on a copy.
Rule is: save always in UTC, save always in the format that the database can parse, then convert for the client.