用递归方法求n!

如何使用PowerDesigner软件进行数据库设计（多对多关系）

DBWG: 文档中说：“To use n..n relationships in an LDM, see Enabling many-to-many relationships in an LDM.”“Enabling Many-to-many Relationships in an LDM In an LDM, many-to-many relationships are, by default, not permitted and are represented with an intermediary entity. If you allow many-to-many relationships, you can select the many-to-many value in the cardinalities tab. Select Tools > Model Optionsto open the Model Options dialog box. Select the Allow n-n relationships check box in the Relationship groupbox, and then click OK to return to the model. Parent topic: Relationship Properties ”