PostgreSQL translate special characters?

**Description:** PostgreSQL 9.3 String: **'ì ằ ú ề'** Desired Result: **'i a u e'** My code: select translate ('ì ằ ú ề', 'ìằúề', 'iaue') ; -- it works. Result: i a u e **Question:** If I use it this way, I have to define a manual translation between 'ìằúề' and 'iaue'. Is there a better solution? Ref: PG Document