Hi,
wondering why OpenJPA's MappingTool refused to add a foreign key constraint
to the database (error message: openjpa.jdbc.Schema - The foreign key
"<foreignkey>" was not added to table "[...]"), I discovered that composite
foreign key support is explicitly disabled for MySQL. These are the relevant
code lines in org.apache.openjpa.jdbc.sql.MySQLDictionary:
protected String getForeignKeyConstraintSQL(ForeignKey fk) {
// mysql does not support composite foreign keys
if (fk.getColumns().length > 1)
return null;
return super.getForeignKeyConstraintSQL(fk);
}
For all I know, composite foreign keys are possible with MySQL. At least, a
statement like
ALTER TABLE detail ADD CONSTRAINT constraint_x FOREIGN KEY (masterId1,
masterId2) REFERENCES master (masterId1, masterId2);
works perfectly well. Are there other deficits with MySQL foreign key
handling I am not aware of or are the above lines in MySQLDictionary.java
outdated / wrong?
Regards,
Martin.
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