NHibernate简化了DLL,但降低了性能?
Northwind的Employee和Territories具有多对多的关系,关系存放在EmployeeTerritories表里。
所以在两个Entity建立many-to-many。
Employees.hbm.xml:
<bag name="EmployeeTerritories" table="EmployeeTerritories" inverse="false" lazy="true" cascade="all-delete-orphan">
<key>
<column name="EmployeeID" length="4" sql-type="int" not-null="true"/>
</key>
<many-to-many class="DataEntity.Territory, DataEntity">
<column name="TerritoryID" length="20" sql-type="nvarchar" not-null="true"/>
</many-to-many>
</bag>
Territories.hbm.xml:
<bag name="TerritoryEmployees" table="EmployeeTerritories" inverse="true" lazy="true" cascade="all-delete-orphan">
<key>
<column name="TerritoryID" length="20" sql-type="nvarchar" not-null="true"/>
</key>
<many-to-many class="DataEntity.Employee, DataEntity">
<column name="EmployeeID" length="4" sql-type="int" not-null="true"/>
</many-to-many>
</bag>
在EmployeeTerritories里,原先Employee有一个记录对应Territories的5条记录,
EmployeeID territoryid
15 01881
15 01882
15 01883
15 01884
15 01885
现在要给这个EmployeeID=15的记录添加新的Territories记录(territoryid=01886)
ISession session = SessionFactory.OpenSession(_AssemblyName);
Employee employee = null;
Territory territory = null;
//try...
//catch...
//finaly...
ITransaction transaction = session.BeginTransaction();
territory = (Territory)session.Get(typeof(Territory), "01886");
transaction.Commit();
transaction = session.BeginTransaction();
employee = (Employee)session.Get(typeof(Employee), 15);
employee.EmployeeTerritories.Add(territory);
session.Update(employee);
transaction.Commit();
用sql查看器查看,发现sql先delete了原来的EmployeeID=15的5条记录,然后再insert这5条记录,再insert新的id=01886的记录,总共执行了7条sql语句
如果原先有上百条记录,那不是要执行几百条记录了?NHibernate中有没有什么配置可以改变?