LLBLGen的数据库相对应SQL语句实现方法收藏

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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);

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.Customer = 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