开放源码的对象关系映射工具ORM.NET 插入数据 Insert/Update Data

DataManager.New[Object] 创建数据记录

下面的代码片断创建一笔学生记录，然后把它保存到数据库中。

DataManager dm = new DataManager(Config.Dsn);
//assign a new object reference
Student s = dm.NewStudent();
s.FirstName = “Mike”;
s.LastName = “Smith”;
dm.CommitAll();

如果是主从关系的数据表，Student和Contact, ORM.NET会帮助处理好它们之间的外键引用关系

DataManager dm= new DataManager(Config.Dsn);
Student s = dm.NewStudent();
s.FirstName = "Tim";
s.LastName = "Brown";

s.Contact = dm.NewContact();
s.Contact.Address1 = "555 Main Street";
s.Contact.Address2 = "Apt 6";
s.Contact.City = "Oakland";
s.Contact.State = "CA";
s.Contact.PostalCode = "80304";
s.Contact.Country = "US";
// create both records and maintain the relationship between them in database
dm.CommitAll();  

增加子对象 Add[ChildObject] Methods

通过Add[Child]方法，可以新加子对象，在CommitAll时，ORM.NET会自动维护它们的主外键关系。

DataManager dm= new DataManager(Config.Dsn);
// Create new Student object
Student student = dm.NewStudent();
student.FirstName = "Cherry";
student.LastName = "Jackson";
// Create a new contact
contact contact = dm.NewContact();
contact.Address1 = "55 6th Avenue";
// add other contact information..
// Add the new Student to the new Contact object
contact.AddStudent(student);
dm.CommitAll();

New[ChildObject] methods

// find an existing Contact record
dm.QueryCriteria.And(JoinPath.Contact.Columns.Address1,"123 Main Street");
Contact contact = dm.GetContact(FetchPath.All);
Student student = contact.NewStudent();  // create a new Child object - Student
student.firstname = "Tom";
student.LastName = "Smith";
//CommitAll() will create a new Student object and relate it to the Contact object
dm.CommitAll();    

如果对象已经在内存中，可以通过NewChild方式，创建新的子对象，在调用CommitAll时，会保存到数据库中。

Using Require Setting on  New[Object] Methods for Column Properties

可以通过在ORM.NET Object Browser中设定属性FirstName为Required，必须输入。与此同时，NewStudent方法签名也会变化，以用于传入FirstName的值。

用于新加新对象的代码如下

//FirstName is now required to create new Student object                   
Student s = dm.NewStudent("Mike"); 
//add a LastName value as well if you like...
s.LastName = Smith;                 
dm.CommitAll();

第一个参数Mike，就是FirstName。一般，只需要将主键字段列设定为Required即可。

Using Require Parent Object New[Object] Methods on Child records

Required属性也可以用在子对象的创建过程中，如下图所示

经过上图所示的设置，在NewObject中的一个方法签名，cocntact是必须输入的。

DataManager dm = new DataManager(Config.Dsn);
// create a new contact object with some information
Contact contact = dm.NewContact();       
contact.Address1 = "123 Require Parent";
contact.City = "Boulder";
contact.Country = "US";
// Contact object is now required
Student student = dm.NewStudent(contact); 
student.FirstName = "John";
student.LastName = "Glass";
// Create the new Student and related Contact record
dm.CommitAll();     

属性与它的父对象可以同时设置为Required，像下面的代码这样

// A FirstName property and Contact object are now required to create a new Student object
Contact = dm.GetContact();
Student student = dm.NewStudent(“Tom”,contact); 

更新数据

DataManager dm = new DataManager(Config.Dsn);
dm.QueryCriteria.Clear();
dm.QueryCriteria.And(JoinPath.Teacher.Columns.FirstName,"Tom",MatchType.Exact);
Teacher teacher = dm.GetTeacher(FetchPath.Teacher);
teacher.FirstName = "Thomas";
teacher.LastName = "Franklin";
dm.CommitAll();      // Will perform required update operation as a transaction

CommitAll方法会生成下面的SQL语句

BEGIN TRANSACTION
UPDATE[Teacher]
    SET    [LastName] = 'Franklin',
           [FirstName] = 'Thomas'
WHERE  ID = 10008

IF @@ERROR <> 0 BEGIN
      ROLLBACK TRANSACTION
      RETURN
END
COMMIT TRANSACTION

DataManager.CommitAllDebug 

如果是调试程序，可以用CommitAllDebug生成所有SQL语句，但不会把SQL提交到数据库中执行。

dm.QueryCriteria.Clear();
dm.QueryCriteria.And(JoinPath.Teacher.Columns.FirstName,"Tom", MatchType.Exact);
Teacher teacher = dm.GetTeacher(FetchPath.Teacher);
teacher.FirstName = "Thomas";
teacher.LastName = "Franklin";
// Will NOT perform any changes but will generate the SQL statement(s) that would be        
// used in the Output window
dm.CommitAllDebug(); 

这时，可以到Output窗口中查看生成SQL语句，以检测逻辑是否正确。

如果是调用DataManager.CommitAll，则可以通过调用它的属性LastCommitText来获取最后一次事务的SQL语句

DataManager dm = new DataManager(Config.Dsn);
dm.QueryCriteria.Clear();
dm.QueryCriteria.And(JoinPath.Teacher.Columns.FirstName,"Tom",MatchType.Exact);
Teacher teacher = dm.GetTeacher(FetchPath.Teacher);
teacher.FirstName = "Thomas";
teacher.LastName = "Franklin";
dm.CommitAll();      
// ouput generated SQL statement to console
Console.WriteLine("OUTPUT SQL " + dm.LastCommitText);