Could someone told me why this isn't working 'select distinct City from Station where substring(City,-1) in ('a', 'u','o','i','e') and substring (City,1,1) in ('A', 'U','O','I','E');' I am recieving that substring function doesn't exist?

SELECT DISTINCT CITY FROM STATION WHERE LEFT(CITY,1) in ('a', 'e','i','o','u') AND RIGHT(CITY,1) in ('a', 'e','i','o','u');

MySQL: SELECT DISTINCT CITY FROM STATION WHERE CITY REGEXP '^[aeiouAEIOU].*[aeiouAEIOU]$' ;

SELECT DISTINCT CITY FROM STATION WHERE LOWER(LEFT(CITY, 1)) IN ('a','e','i','o','u') AND LOWER(RIGHT(CITY, 1)) IN ('a','e','i','o','u');

ora: select distinct CITY
from STATION where regexp_like(upper(CITY), '^AEOIU[AEOIU]$');