Net框架下-ORM框架LLBLGen的简介

using SD.LLBLGen.Pro.ORMSupportClasses;

using FactoryClasses；

using HelperClasses；

using RelationClasses；

using DBAdapter;

using EntityClasses；

using ViewClasses；

namespace ORM_Demo{
　　public class BLLCFUser：IBLLCFUser{

　　　　按照规则自动生成的方法代码,如下示例...(借鉴内部资料的整理)
　　}
}


1、视图查询

例: Select * From View_CF_User_All Where RecordStatus<>‘InActive‘ Order By UserID Desc
public ViewCFUserAllTypedView FetchAllUser()
{
    DataAccessAdapter adapter = new DataAccessAdapter();
    try
    {
         ViewCFUserAllTypedView user = new ViewCFUserAllTypedView();
         RelationPredicateBucket bucket = new RelationPredicateBucket();
         SortExpression sorter = new SortExpression();
         //加过滤条件
         bucket.PredicateExpression.Add(ViewCFUserAllFields.RecordStatus != "InActive");
         //加排序条件
         sorter.Add(ViewCFUserAllFields.UserID | SortOperator.Descending);               
         adapter.FetchTypedView(user.GetFieldsInfo(), user, bucket, 0, sorter, true);
         return user;
    }
    catch
    {
        return null;
    }
    finally

    {
        adapter.Dispose();
    }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();
ViewCFUserAllTypedView user = orm.FetchAllUser();
if (user != null)
{
    gridView.DataSource = user;
    gridView.DataBind();
}

2、表（记录集合）查询
例: Select * From CF_User
public EntityCollection<DerivedCFUserEntity> FetchUser()
{
    DataAccessAdapter adapter = new DataAccessAdapter();
    try
   {
          EntityCollection<DerivedCFUserEntity> user = new EntityCollection<DerivedCFUserEntity>(new DerivedCFUserEntityFactory());
          RelationPredicateBucket bucket = new RelationPredicateBucket();
          SortExpression sorter = new SortExpression();
          adapter.FetchEntityCollection(user, bucket, 0, sorter);
          return user;
    }
    catch
    {
          return null;
    }
    finally
    {
         adapter.Dispose();
    }
}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();
EntityCollection<DerivedCFUserEntity> user = orm.FetchUser();
if (user != null)
{
    gridView.DataSource = user;
    gridView.DataBind();
}

3、表（某一记录）查询
例: Select * From CF_User Where LoginName=‘Admin‘ And RecordStatus<>‘Inactive‘
public DerivedCFUserEntity FetchUserInfo(string loginName)
{
     DataAccessAdapter adapter = new DataAccessAdapter();
     try
     {
         DerivedCFUserEntity user = new DerivedCFUserEntity();
         RelationPredicateBucket bucket = new RelationPredicateBucket();
         bucket.PredicateExpression.Add(CFUserFields.LoginName == loginName);
         bucket.PredicateExpression.AddWithAnd(CFUserFields.RecordStatus != "Inactive");
         user = (DerivedCFUserEntity)adapter.FetchNewEntity(new DerivedCFUserEntityFactory(), bucket);
         return user;
     }
     catch
     {
         return null;
     }
     finally
     {
        adapter.Dispose();
     }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();
DerivedCFUserEntity user = orm.FetchUserInfo("Admin");
if (user.UserID>0)
{
    lblLoginName.Text = user.LoginName;
}


3-2、多表(多表查询 Linq实现)

》》
using (DataAccessAdapter adapter = new DataAccessAdapter())
{
    LinqMetaData metaData = new LinqMetaData(adapter);
    var q = from t1 in metaData.CFEmployee
        join t2 in metaData.CFCompany on t1.CompanyID equals t2.CompanyID
        where t1.CompanyID < 100
        select new { Addr = (t2.IRDAddress ?? "No Address"), t2.CreateUserID };
}
相当于
select IsNull(t2.IRDAddress,"No Address"),t2.CreateUserID
from CFEmployee as t1
inner join CFCompany as t2 on t1.CompanyID = t2.CompanyID
where t1.CompanyID < 100


》》
 using (DataAccessAdapter adapter = new DataAccessAdapter())

  {

       List<int> ids = new List<int>() { 1, 2, 3 };

       LinqMetaData metaData = new LinqMetaData(adapter);

       var q = from t1 in metaData.CFUser

               where ids.Contains(t1.UserID)

               select t1;

   }

等同于SELECT * FROM CF_USER WHERE USERID IN (1, 2, 3)


》》

using (DataAccessAdapter adapter = new DataAccessAdapter())
{
       LinqMetaData metaData = new LinqMetaData(adapter);
       var q = from t1 in metaData.CFUser
               join t2 in metaData.CFEmployee on
               new { C = t1.RefRecordID, B = t1.CreateUserID }
               equals new { C = t2.EmployeeID, B = t2.CreateUserID }
               join t3 in metaData.CFAccount on
               new { D = t1.CreateUserID, E = t1.ModifyUserID }
              equals new { D = t3.CreateUserID, E = t3.ModifyUserID }
              select t1;
}

等同于

SELECT LPA_L1.* FROM [CF_User] as [LPA_L1]  
INNER JOIN [CF_Employee] as [LPA_L2]  
ON  ( [LPA_L1].[RefRecordID] = [LPA_L2].[EmployeeID] AND [LPA_L1].[CreateUserID] = [LPA_L2].[CreateUserID]))
INNER JOIN [CFAccount] as [LPA_L3]  
ON  ( [LPA_L1].[CreateUserID] = [LPA_L3].[CreateUserID]) AND  [LPA_L1].[ModifyUserID] = [LPA_L3].[ModifyUserID])



4、Insert操作（单表记录新增）

例: Insert CF_User(A,B,C) Values(……)

public bool Add(string loginName, string password)

{
    DataAccessAdapter adapter = new DataAccessAdapter();
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
    try
    {
        DerivedCFUserEntity user = new DerivedCFUserEntity();
        user.PrivClassID = 8;
        user.RefTable = "CF_Employee";
        user.RefRecordID = 1;
        user.LoginName = loginName;
        user.Password = password;
        user.LanguageSelect = "CN";
        user.IsManager = "N";
        user.RegionalSetting = "zh-CN";
        user.RecordStatus = "Active";
        user.CreateUserID = 1;
        user.CreateDate = DateTime.Now;
        user.ModifyUserID = 1;
        user.ModifyDate = DateTime.Now;
        adapter.SaveEntity(user);
        adapter.Commit();
        return true;
    }
    catch
   {
        adapter.Rollback();
        return false;
    }
    finally
    {
        adapter.Dispose();
    }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();

string loginName = "Amdin";
string password = "111111";

if (orm.Add(loginName, password))
{
    Alert("Success");
}
else
{
    Alert("Fail");
}

5、Update操作（单表记录修改）

例: Update CF_User Set RecordStatus=‘Inactive‘ Where UserID=100 //主键条件

public bool Modify(int userID)
{
    DataAccessAdapter adapter = new DataAccessAdapter();
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
    try
    {
        DerivedCFUserEntity user = new DerivedCFUserEntity(userID);                
        if (user.UserID < 1)
        {
            return false;
        }
        else
        {
             user.IsNew = false;
             adapter.FetchEntity(user);
             user.RecordStatus = "Inactive";
             adapter.SaveEntity(user);
             adapter.Commit();
             return true;                   
        }               

   }
    catch
    {
         adapter.Rollback();
         return false;
    }
    finally
    {
         adapter.Dispose();
    }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();
int userID = 100;
if (orm. Modify(userID))
{
    Alert("Success");
}
else
{
    Alert("Fail");
}

Update操作（单表按条件多条记录修改）

例: Update CF_User Set RecordStatus=‘Inactive‘，ModifyDate=getdate() Where LoginName=‘Admin‘ and IsManager=‘N‘  //非主键条件
public bool Modify(string LoginName，string IsManager)
{
    DataAccessAdapter adapter = new DataAccessAdapter();
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
    try
    {                
        RelationPredicateBucket bucket = new RelationPredicateBucket();
        bucket.PredicateExpression.Add(DerivedCFUserFields.LoginName == LoginName);
        bucket.PredicateExpression.Add(DerivedCFUserFields.IsManager == IsManager);

    DerivedCFUserEntity updateValues = new DerivedCFUserEntity();
    updateValues.RecordStatus = HRRecordStatus.Inactive;
    updateValues.ModifyDate = DateTime.Now;

    int AmountUpdated = adapter.UpdateEntitiesDirectly(updateValues, bucket); 
           
    adapter.Commit();
        return true;  
   }
    catch
    {
         adapter.Rollback();
         return false;
    }
    finally
    {
         adapter.Dispose();
    }

}

6、Delete操作（单表记录删除）

例: Delete From CF_User Where UserID=100

public bool Delete(int userID)

{
    DataAccessAdapter adapter = new DataAccessAdapter();
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
    try
    {
       DerivedCFUserEntity user = new DerivedCFUserEntity(userID);               
        if (user.UserID < 1)
        {
            return false;
        }
        else
        {
             adapter.FetchEntity(user);
             //进行删除操作
             adapter.DeleteEntity(user);
             adapter.SaveEntity(user);
             adapter.Commit();
             return true;                   

        }               

   }
    catch
    {
         adapter.Rollback();
         return false;
    }
    finally
    {
         adapter.Dispose();

    }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();

int userID = 100;

if (orm.Delete(userID))

{

    Alert("Success");

}

else

{

    Alert("Fail");

}

Delete操作（单表按条件多条记录删除）

例: Delete From CF_User Where CompanyID=100 and DeptID=34

public bool Delete(int CompanyID,int DeptID)

{
    DataAccessAdapter adapter = new DataAccessAdapter();
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
    try
    {
    RelationPredicateBucket bucket = new RelationPredicateBucket();
    bucket.PredicateExpression.Add(DerivedCFUserFields.CompanyID == CompanyID);
    bucket.PredicateExpression.Add(DerivedCFUserFields.DeptID == DeptID);

    int AmountUpdated = adapter.DeleteEntitiesDirectly(typeof(DerivedCFUserEntity), bucket);
    adapter.Commit();
    return true;  
   }
    catch
    {
         adapter.Rollback();
         return false;
    }
    finally
    {
         adapter.Dispose();

    }

}


7、Insert操作（多表记录新增）

例: Insert CF_Employee(…………………………) Values(……………………………………)

Insert CF_User(…………………………) Values(……………………………………)

public bool Add(string loginName, string password, string firstName, string lastName, string employeeNo)

{

   DataAccessAdapter adapter = new DataAccessAdapter();

    adapter.StartTransaction(IsolationLevel.ReadCommitted, "");

    try

    {

        int employeeID;

        //再保存CF_Employee的信息

        DerivedCFEmployeeEntity employee = new DerivedCFEmployeeEntity();

        employee.FirstName = firstName;

        employee.LastName = lastName;

        employee.EmployeeNo = employeeNo;

        employee.ActingSupervisor = "N";

       employee.IsAllowProxy = "N";

        employee.DefaultLanguage = "CN";

        employee.RecordStatus = "Active";

        employee.CreateUserID = 1;

        employee.CreateDate = DateTime.Now;

        employee.ModifyUserID = 1;

        employee.ModifyDate = DateTime.Now;

        adapter.SaveEntity(employee, true);

        //保存CF_Employee后获取出EmployeeID
        employeeID = employee.EmployeeID;

       //再保存CF_User的信息

        DerivedCFUserEntity user = new DerivedCFUserEntity();

       user.PrivClassID = 8;

        user.RefTable = "CF_Employee";

        //用到CF_Employee表中的EmployeeID

        user.RefRecordID = employeeID;

       user.LoginName = loginName;

        user.Password = password;

        user.LanguageSelect = "CN";

        user.IsManager = "N";

        user.RegionalSetting = "zh-CN";

       user.RecordStatus = "Active";

        user.CreateUserID = 1;

        user.CreateDate = DateTime.Now;

        user.ModifyUserID = 1;

        user.ModifyDate = DateTime.Now;

        adapter.SaveEntity(user);

       adapter.Commit();

        return true;

    }

    catch

    {

         adapter.Rollback();

         return false;

    }

    finally

    {

         adapter.Dispose();

}

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();

string loginName = "Amdin";

string password = "111111";

string firstName = "李";

string lastName = "小龙";

string employeeNo = "0532";

if (orm.Add(loginName, password, firstName, lastName, employeeNo))

{
    Alert("Success");
}
else
{
    Alert("Fail");
}

8、Update操作（多表记录修改）

例: Update CF_User Set RecordStatus=‘Inactive‘ Where UserID=100

Update CF_Employee Set RecordStatus=‘Inactive‘ Where EmployeeID=200

public bool Modify(int userID, int employeeID)

{
     DataAccessAdapter adapter = new DataAccessAdapter();

     adapter.StartTransaction(IsolationLevel.ReadCommitted, "");

     try

     {

         DerivedCFUserEntity user = new DerivedCFUserEntity(userID);

         DerivedCFEmployeeEntity employee = new DerivedCFEmployeeEntity(employeeID);

         if (user.UserID < 1 || employeeID < 0)

         {

             return false;

         }

         else

         {

             //更新CF_User的记录

             user.IsNew = false;

             adapter.FetchEntity(user);

             user.RecordStatus = "Inactive";

             adapter.SaveEntity(user);

             //更新CF_Employee的记录

             employee.IsNew = false;

             adapter.FetchEntity(employee);

             employee.RecordStatus = "Inactive";

             adapter.SaveEntity(employee);

            
             adapter.Commit();

             return true;
         }
     }
     catch
     {
          adapter.Rollback();

          return false;
     }

     finally

     {

          adapter.Dispose();

     }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();

int userID = 100;

int employeeID = 200;

if (orm. Modify(userID,employeeID))

{

    Alert("Success");

}

else

{
    Alert("Fail");
}

9、Delete操作（多表记录删除）

例: Delete From CF_User Where UserID=100

    Delete From CF_Employee Where EmployeeID=200

public bool Delete(int userID, int employeeID)

{
     DataAccessAdapter adapter = new DataAccessAdapter();
     adapter.StartTransaction(IsolationLevel.ReadCommitted, "");
     try
     {

         DerivedCFUserEntity user = new DerivedCFUserEntity(userID);

         DerivedCFEmployeeEntity employee = new DerivedCFEmployeeEntity(employeeID);

         if (user.UserID < 1 || employeeID < 0)
         {
             return false;
         }
         else
         {
             //删除CF_User中的记录

             adapter.FetchEntity(user);                   

             adapter.DeleteEntity(user);

 
             //删除CF_Employee中的记录

             adapter.FetchEntity(employee);

             adapter.DeleteEntity(employee);
           
             adapter.Commit();

             return true;
         }
     }
     catch
     {
          adapter.Rollback();
          return false;
     }
     finally
     {
          adapter.Dispose();
     }

}

对生成代码的调用e.g

ORM_Demo orm = new ORM_Demo();

int userID = 100;

int employeeID = 200;

if (orm.Delete(userID,employeeID))
{
    Alert("Success");
}
else
{
    Alert("Fail");
}



示例二:


1、
CustomerEntity customer = new CustomerEntity();定义一个空新实体
CustomerEntity customer = new CustomerEntity("SOLDES");定义一个主键值为"SOLDES"的新实体

2、
DataAccessAdapter adapter = new DataAccessAdapter();
CustomerEntity customer = new CustomerEntity("CHOPS");
adapter.FetchEntity(customer);
return customer;

直接从数据库中取一条主键为"CHOPS"的记录。它不会存在cache中。
相当于SQL: select * from customers where customerID=‘CHOPS‘
根据主键来返回一条记录

3、
DataAccessAdapter adapter = new DataAccessAdapter(true);
OrderEntity order = new OrderEntity(10254);
adapter.FetchEntity(order);

order.Customer = (CustomerEntity)adapter.FetchNewEntity(new CustomerEntityFactory(),order.GetRelationInfoCustomer());
adapter.CloseConnection();

相当于SQL: Select * from customers where CustomerID= (select CustomerID from orders where OrderID=10254)
在这里，order为customer的子表，先从order表中取一条OrderID=10254的记录，然后再取与这一条记录相关联的Customer的记录。

4、
DataAccessAdapter adapter = new DataAccessAdapter();
CustomerEntity customer = new CustomerEntity();
customer.CompanyName = "Chop-suey Chinese";
adapter.FetchEntityUsingUniqueConstraint(customer, customer.ConstructFilterForUCCompanyName());

相当于SQL: select * from customerS where CompanyName =‘Chop-suey Chinese‘但是这里CompanyName必须也是唯一的

5、
CustomerEntity customer = new CustomerEntity("CHOPS");
DataAccessAdapter adapter = new DataAccessAdapter(true);
adapter.FetchEntity(customer);
customer.Phone = "(605)555-4321";
adapter.SaveEntity(customer);
adapter.CloseConnection();

相当于SQL: update customerS set phone=‘(605)555-4321‘ where customerID=‘Chop-suey Chinese‘
//更新一条记录的一个字段

6、
RelationPredicateBucket bucket = new RelationPredicateBucket();
bucket.PredicateExpression.Add(ProductFields.CategoryId == 3);

ProductEntity updateValuesProduct = new ProductEntity();
updateValuesProduct.Discontinued=true;
DataAccessAdapter adapter = new DataAccessAdapter();
int amountUpdated =adapter.UpdateEntitiesDirectly(updateValuesProduct, bucket);

相当于SQL: update products set Discontinued=1 where CategoryId = 3
更新CategoryId = 3的所有记录

7、
PrefetchPath2 path = new PrefetchPath2((int)EntityType.OrderEntity);
path.Add(OrderEntity.PrefetchPathCustomer);

OrderEntity myOrder = new OrderEntity(10254);
adapter.FetchEntity(myOrder, path); 
           
myOrder.CustomerID = null;
adapter.save(myOrder);

相当于SQL: Update Orders  set CustomerID=NULL  where  OrderID=10254

8、DataAccessAdapter adapter = new DataAccessAdapter(true);
CustomerEntity customer = new CustomerEntity("CHOPS");

adapter.DeleteEntity(customer);

adapter.CloseConnection();

相当于SQL: Delete customers where customerID=‘CHOPS‘

9、
OrderEntity order = new OrderEntity(10254);

DataAccessAdapter adapter = new DataAccessAdapter();

adapter.FetchEntity(order);

order.SetNewFieldValue((int)OrderFieldIndex.ShippingDate, null);

adapter.SaveEntity(order);

相当于SQL: Update Orders Set ShippedDate=null  Where OrderID=10254
这种写法将不会执行数据验证，使用时要注意这个问题！
也可以这样写：

OrderEntity order = new OrderEntity(10254);
DataAccessAdapter adapter = new DataAccessAdapter();

adapter.FetchEntity(order);

order.ShippingDate = null;

adapter.SaveEntity(order);

10、CustomerEntity customer = new CustomerEntity("CHOPS");
customer.SetNewFieldValue((int)CustomerFieldIndex.ContactTitle, null);

customer.TestCurrentFieldValueForNull(CustomerFieldIndex.ContactTitle); 

// returns true 

检测一个字段值是否为NULL

11、CustomerEntity customer = new CustomerEntity("CHOPS");
DataAccessAdapter Adapter = new DataAccessAdapter();

EntityCollection orders = customer.Orders;

Adapter.FetchEntityCollection(orders, customer.GetRelationInfoOrders());

相当于SQL: Select * from  Orders where CustomerID=‘CHOPS‘

通过主表的一个主键值查找与这个主键相关联的子表的记录

以下这种办法也可以：

CustomerEntity customer = new CustomerEntity("CHOPS");
DataAccessAdapter Adapter = new DataAccessAdapter();

Adapter.FetchEntityCollection(customer.orders, customer.GetRelationInfoOrders());

12、 
EntityCollection<CustomerEntity> customers =new EntityCollection<CustomerEntity>(new CustomerEntityFactory());
DataAccessAdapter adapter = new DataAccessAdapter();
adapter.FetchEntityCollection(customers, null);

customers.Sort((int)CustomerFieldIndex.CompanyName, ListSortDirection.Descending);

相当于SQL:  Select * From Customers Order By CompanyName desc 

IPredicate filter = (CustomerFields.Country == "UK");
ArrayList indexes = myCustomers.FindMatches(filter); 

这样只在前面的myCustomers 中查找Country == "UK"的记录，不会去数据库中查找。

13、
EntityCollection<CustomerEntity> customers = new EntityCollection<CustomerEntity>();
PrefetchPath2 path = new PrefetchPath2(EntityType.CustomerEntity);
path.Add(CustomerEntity.PrefetchPathOrders).SubPath.Add(OrderEntity.PrefetchPathEmployees);
using(DataAccessAdapter adapter = new DataAccessAdapter())
{
    adapter.FetchEntityCollection(customers, null, path);
}
这里一共取了三个表的数据，主表为customers及其的子表Orders及Orders的主表Employess。

14、using (DataAccessAdapter adapter = new DataAccessAdapter())

            {

                DataTable table = new DataTable();

                table.Columns.Add("CustomerId", typeof(string));

                table.Columns.Add("CompanyName", typeof(string));

                table.Columns.Add("OrderId", typeof(string));

                ResultsetFields fields = new ResultsetFields(3);

                fields[0] = CustomersFields.CustomerId;

                fields[1] = CustomersFields.CompanyName;

                fields[2] = OrdersFields.OrderId;

                RelationPredicateBucket filter = new RelationPredicateBucket(CustomersFields.Country == "Germany");

                filter.Relations.Add(CustomersEntity.Relations.OrdersEntityUsingCustomerId);

                IDataReader reader = adapter.FetchDataReader(fields, filter, CommandBehavior.CloseConnection, 0, true);

                while (reader.Read())

                {

                    table.Rows.Add(reader.GetValue(0).ToString(), reader.GetValue(1).ToString(), reader.GetValue(2).ToString());

                }

                reader.Close();

           } 

这是同时从两个表中查找记录的办法

相当于SQL:  select customers.customerid,customers.CompanyName from customers  where  customers.Country = ‘USA‘ 

15、
EntityCollection employees = new EntityCollection(new EmployeesEntityFactory());

        IPrefetchPath2 prefetchPath = new PrefetchPath2((int)EntityType.EmployeesEntity);

        ISortExpression sorter = new SortExpression();

        sorter.Add(OrdersFields.OrderDate | SortOperator.Descending);

        prefetchPath.Add(EmployeesEntity.PrefetchPathOrders, 10, null, null, sorter);

        DataAccessAdapter adapter = new DataAccessAdapter();

     adapter.FetchEntityCollection(employees,null, prefetchPath);

相当于SQL: select * from employees  假设第一条记录的employeeid=1

 select top 10 * from  orders where employeeid=1 order by orderid desc

 

16、
ExcludeIncludeFieldsList excludedFields = new ExcludeIncludeFieldsList();
excludedFields.Add(CustomerFields.ContactName);

excludedFields.Add(CustomerFields.Country);

 
EntityCollection customers = new EntityCollection(new EmployeesEntityFactory());
SortExpression sorter = new SortExpression(CustomersFields.CustomerId | SortOperator.Descending);

using(DataAccessAdapter adapter = new DataAccessAdapter())
{
    adapter.FetchEntityCollection(customers, null, 0, sorter, null, excludedFields);
}

相当于SQL: Select ContactName,Country from customers order by CustomerId  desc


CustomersEntity c = new CustomersEntity("CHOPS");
using(DataAccessAdapter adapter = new DataAccessAdapter())

{
        adapter.FetchEntity(c, null, null, excludedFields);
}

相当于SQL: 
Select ContactName,Country from customers Where CustomerId =‘CHOPS‘


using(DataAccessAdapter adapter = new DataAccessAdapter())
{
        adapter.FetchExcludedFields(customers, excludedFields);
        adapter.FetchExcludedFields(c, excludedFields);
}

也可以这样写

17、
ExcludeIncludeFieldsList excludedFields = new ExcludeIncludeFieldsList();
excludedFields.Add(OrdersFields.OrderDate);

PrefetchPath2 path = new PrefetchPath2(EntityType.CustomersEntity);
path.Add(CustomersEntity.PrefetchPathOrders, excludedFields);

EntityCollection customers = new EntityCollection(new CustomersEntityFactory());
using (DataAccessAdapter adapter = new DataAccessAdapter())
{
    adapter.FetchEntityCollection(customers, null, 25, null, path);
}

18、 DataAccessAdapter adapter = new DataAccessAdapter();

     // 开始一个事务

     adapter.StartTransaction(IsolationLevel.ReadCommitted, "TwoUpates");
          try
            {
                CustomersEntity customer = new CustomersEntity("CHOPS");
                OrdersEntity order = new OrdersEntity(10254);
                adapter.FetchEntity(customer);
                adapter.FetchEntity(order);
                // 修改字段
                customer.Fax = "12345678";
                order.Freight = 12; 

                // 保存
                adapter.SaveEntity(customer);
                adapter.SaveEntity(order); 

                // 提交
                adapter.Commit();
            }
         catch
            {
                //出错回滚
                adapter.Rollback();
                throw;
            }
        finally
            {
                // 销毁
                adapter.Dispose();
          }

19、以下是一个更好的方法

DataAccessAdapter adapter = new DataAccessAdapter();
try
{
    adapter.StartTransaction(IsolationLevel.ReadCommitted, "SavepointRollback");
    AddressEntity newAddress = new AddressEntity();
    adapter.SaveEntity(newAddress, true);

     adapter.SaveTransaction("SavepointAddress");

     CustomersEntity newCustomer = new CustomersEntity();
    newCustomer.VisitingAddress = newAddress;
    newCustomer.BillingAddress = newAddress;
    try
    {
        adapter.SaveEntity(newCustomer, true);
    }
    catch (Exception ex)
    {
        adapter.Rollback("SavepointAddress");
    }
    adapter.Commit();
    }
    catch
    {
        adapter.Rollback();
        throw;
    }
    finally
    {
        adapter.Dispose();
    }

21、
IRelationPredicateBucket filter = new RelationPredicateBucket();
filter.PredicateExpression.Add(CustomersFields.Country == "France");
filter.Relations.Add(OrdersEntity.Relations.CustomersEntityUsingCustomerId);
DataAccessAdapter adapter = new DataAccessAdapter();
int amount = (int)adapter.GetDbCount(new
OrdersEntityFactory().CreateFields(), filter, null, false);

相当于SQL: 

Select count (*) from orders,customers Where Country = ‘France‘  and customers.customerID=ORDERS.customerID

22、protected override void SerializeOwnedData(SerializationWriter writer, object context)
{
    base.SerializeOwnedData(writer, context);
    writer.WriteOptimized(this.OrderId);
}

protected override void DeserializeOwnedData(SerializationReader reader,object context)
{
    base.DeserializeOwnedData(reader, context);
    this.OrderId = reader.ReadOptimizedInt32();
}

23、
PredicateExpression filter = new PredicateExpression();

filter.Add(new FieldBetweenPredicate(OrdersFields.OrderDate,null, new DateTime(1996, 8, 1), new DateTime(1996, 8, 12)));

RelationPredicateBucket bucket = new RelationPredicateBucket();
bucket.PredicateExpression.Add(filter);
EntityCollection customers = new EntityCollection(new OrdersEntityFactory());
using (DataAccessAdapter adapter = new DataAccessAdapter())
{
    adapter.FetchEntityCollection(customers, bucket);
}

 相当于SQL: 

Select * from orders  where orderdate between ‘1996-08-01‘ and ‘1996-08-12‘

24、
EntityCollection Orders= new EntityCollection(new OrdersEntityFactory());

     RelationPredicateBucket bucket = new RelationPredicateBucket();

   bucket.PredicateExpression.Add(OrdersFields.ShippedDate==System.DBNull.Value); 

            using (DataAccessAdapter adapter = new DataAccessAdapter())

            {

                adapter.FetchEntityCollection(Orders, bucket);

            }

相当于SQL: select * from orders where shippeddate is null

也可以这样写：

bucket.PredicateExpression.Add(new FieldCompareNullPredicate(OrdersFields.ShippedDate,null ,false));

25、
EntityCollection customers = new EntityCollection(new OrdersEntityFactory());

    RelationPredicateBucket bucket = new RelationPredicateBucket();

    DateTime[] values = new DateTime[3] { new DateTime(1998,04,8), new DateTime(1998,4,13), new DateTime(1998,4,21)};

    bucket.PredicateExpression.Add(new FieldCompareRangePredicate(OrdersFields.OrderDate,null, values)); 

    using (DataAccessAdapter adapter = new DataAccessAdapter())

       {

             adapter.FetchEntityCollection(customers, bucket);

       }

相当于SQL:

 select * from orders where OrderDate in (‘1998-04-08‘ ,‘1998-04-13‘,‘1998-04-21‘) 

也可以这样写：

bucket.PredicateExpression.Add(OrderFields.OrderDate == values);//里面是数组

26、
EntityCollection customers = new EntityCollection(new CustomersEntityFactory());

    RelationPredicateBucket bucket = new RelationPredicateBucket();

    bucket.Relations.Add(CustomersEntity.Relations.OrdersEntityUsingCustomerId);

    bucket.PredicateExpression.Add(new FieldCompareSetPredicate(

 CustomersFields.CustomerId,null, OrdersFields.CustomerId,null,

                                SetOperator.In, (OrdersFields.EmployeeId == 9))); 

    using (DataAccessAdapter adapter = new DataAccessAdapter())

       {

           adapter.FetchEntityCollection(customers, bucket);

       }

相当于SQL:

select * from customers where   Customers.CustomerID IN (SELECT CustomerID FROM Orders WHERE Employeeid=9)

27、
EntityCollection customers = new EntityCollection(new CustomersEntityFactory());

    RelationPredicateBucket bucket = new RelationPredicateBucket();

    bucket.PredicateExpression.Add(new FieldLikePredicate (CustomersFields.CompanyName ,null, "%n"));

    using (DataAccessAdapter adapter = new DataAccessAdapter())

        {

            adapter.FetchEntityCollection(customers, bucket);

        }

相当于SQL:

select * from customers where companyname like ‘%n‘

也可以这样写：

bucket.PredicateExpression.Add(CustomersFields.CompanyName % "%n");

28、
ResultsetFields fields = new ResultsetFields(2);
fields.DefineField(CustomersFieldIndex.Country, 0, "Country");
fields.DefineField(CustomersFieldIndex.CustomerId, 1, "AmountCustomers");
fields[1].AggregateFunctionToApply = AggregateFunction.CountDistinct;
DataAccessAdapter adp = new DataAccessAdapter();
DataTable table = new DataTable();
IGroupByCollection groupByClause = new GroupByCollection();

groupByClause.Add(fields[0]);
groupByClause.Add(fields[1]);
adp.FetchTypedList(fields, table, null, 0, null, false, groupByClause);

29、
DataAccessAdapter adapter = new DataAccessAdapter();
decimal orderPrice = (decimal)adapter.GetScalar(OrderDetailsFields.OrderId,(OrderDetailsFields.Quantity * OrderDetailsFields.UnitPrice), AggregateFunction.Sum, (OrderDetailsFields.OrderId == 10254));

相当于SQL:
select sum(unitprice*quantity) from [Order Details] where orderid=10254

30、
ResultsetFields fields = new ResultsetFields(3);
fields.DefineField(OrderDetailsFields.OrderId, 0);
fields.DefineField(OrderDetailsFields.ProductId, 1);
fields.DefineField(new EntityField2("RowTotal",(OrderDetailsFields.UnitPrice * OrderDetailsFields.Quantity)), 2);

DataTable results = new DataTable();
DataAccessAdapter adapter = new DataAccessAdapter();
adapter.FetchTypedList(fields, results, null);

相当于SQL:

SELECT OrderID,ProductID,(UnitPrice * Quantity) AS RowTotal FROm [Order Details]

31、
ResultsetFields fields = new ResultsetFields(2);
fields.DefineField(CustomersFields.CustomerId, 0);
fields.DefineField(new EntityField2("NumberOfOrders", new

ScalarQueryExpression(OrdersFields.OrderId.SetAggregateFunction(AggregateFunction.Count),(CustomersFields.CustomerId == OrdersFields.CustomerId))), 1);
DataTable results = new DataTable();
DataAccessAdapter adapter = new DataAccessAdapter();
adapter.FetchTypedList(fields, results, null);

相当于SQL:

SELECT CustomerID,(SELECT COUNT(*) FROM Orders   WHERE CustomerID = Customers.CustomerID) AS NumberOfOrders FROM Customers