How to Displays the maximum number in the string type column in the table using MySQL SUBSTRING

My column name is “momor_request” and my data is :

  • 1000/REPORT/2022
  • 999/REPORT/2022

If iám using SQL Query :

SELECT MAX(SUBSTRING_INDEX(nomor_request,'/',1)) AS max_number FROM my_table

It will show :
999

How to display the max value is (1000)