MySQL with JPA: Illegal mix of collations (utf8mb4

问题:

I need to be able to store characters like \xF0\x9F\x94\xA5 in my database, which, according to this post need UTF8mb4 encoding.

So I set up my database with

CREATE DATABASE `myDB` CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci

and verified in the MySQL shell if it was effective:

SHOW FULL COLUMNS FROM myTable;

+---------+------------------+--------------------+----
| Field   | Type             | Collation          | ...
+---------+------------------+--------------------+-----
| id      | int(10) unsigned | NULL               | ...   
| myColumn| text             | utf8mb4_general_ci | ...
+---------+------------------+--------------------+-----

So far so good.

After running my program, I got this Exception:

Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE) for operation 'like'
Error Code: 1267

For the record: I am using the Java Persistency API (JPA) in my webapplication with GlassFish 3.1. The Exception gets thrown when executing a named query:

@NamedQuery(name = "myTable.findByMyColumn", query = "SELECT c FROM myTable c WHERE c.myColumn LIKE :myColumn")

However, it appears that the error only occurs when the queried String actually contains those weired emoji characters (\xF0\x9F\x94\xA5)

Call: SELECT id, myColumn FROM myDB.myTable WHERE myColumn LIKE ?
bind => [Something something Lorem Ipsum