how to select max of mixed strin

SELECT MAX(CAST(SUBSTRING(invoice_number, 4, length(invoice_number)-3) AS UNSIGNED)) FROM table

SELECT MAX(CAST(ID AS UNSIGNED)) FROM Read_UserSentence

https://stackoverflow.com/questions/16496874/how-to-select-max-of-mixed-string-int-column

https://stackoverflow.com/questions/5477762/using-cast-with-max-min