table user_general has a field named user_name which is varchar(40) now. I want to make it varchar(15). Here is SQL I use:

ALTER TABLE user_general
ALTER COLUMN user_name TYPE varchar(15)

it gives me error:

SQL error:
ERROR: syntax error at or near "TYPE" at character 50
In statement:
ALTER TABLE user_general
ALTER COLUMN user_name TYPE varchar(15)