代码生成器系列（数据库元数据）

<table name="class" comment="班级表">
   <field name="id"          type="int"      length="4" comment="班级编号" PrimaryKey="1">
   <field name="headTeacher" type="nvarchar" length="4" comment="班主任">
</table>

<table name="student" comment="学生表">
   <field name="id"         type="int"      length="4"   comment="学号" PrimaryKey="1">
   <field name="ClassId"    type="int"      length="4"   comment="班级编号">
   <field name="name"       type="nvarchar" length="4"   comment="名字">
   <field name="BirtherDay" type="date"     length="8"   comment="生日">
   <field name="address"    type="nvarchar" length="200" comment="住址">
</table>

<ForeignKey name="FK_Student_ClasssId">
   <Primary Table="student" field="ClasssId">
   <Foreign Table="class"   field="id">
</ForeignKey>