Convert (Excel date) 5 digit numbers to date in mysql

conv_5num_to_date.sql

SELECT 
  iar_d AS date_5_num, /* numbers like: 40479, 40298, 39038, 41075 */
  DATE('1899-12-30') + INTERVAL iar_d DAY AS normal_date /* converted dates */
FROM registry_private_clinics
WHERE iar_d REGEXP '^[0-9]{5}$' /* only rows with NNNNN format, where N is [0-9] */

Thank you for this snippet! Worked like a charm for me.

Thank you!

Wonderful!