Dsync generated code does not work with MySQL

[longsleep]

The generated code from dsync (for create and update) uses get_result which implicitly adds a RETURNING to the generated SQL statement. MySQL does not support RETURNING hence, the trait check for generated code fails as the MysqlConnection does not implement the SupportsReturningClause marker trait.

Instead the create and update functions should use execute and leave it to the caller if it is needed to actually load the data after insert or update.