switch op.Type {
		case clause.OpUnlink:
			return assocDB.Updates(fkNil).Error
		case clause.OpDelete:
			return assocDB.Delete(assocModel).Error
		case clause.OpUpdate:
			return assocDB.Updates(setMap).Error
		}
	case schema.BelongsTo:
		switch op.Type {
		case clause.OpDelete:
			return base.Transaction(func(tx *DB) error {
				assocDB.Statement.ConnPool = tx.Statement.ConnPool

	}

	// Test different association operation types
	operations := []struct {
		Type     clause.AssociationOpType
		TypeName string
	}{
		{clause.OpUnlink, "OpUnlink"},
		{clause.OpDelete, "OpDelete"},
		{clause.OpUpdate, "OpUpdate"},
		{clause.OpCreate, "OpCreate"},
	}

	for _, op := range operations {
		assoc := clause.Association{
			Association: "Orders",
			Type:        op.Type,