📅  最后修改于: 2020-11-19 05:32:11             🧑  作者: Mango
在本章中,我们将介绍基本的CRUD操作。既然我们的系统已经准备好启动,并且已经成功实现了我们的域Student类,那么我们还定义了映射文件并配置了NHibernate。现在,我们可以使用一些查询来执行CRUD操作。
如您所见, NHibernateDemoDB数据库的Student表中没有数据。
因此,要添加一些数据,我们需要执行添加/创建操作,如下所示。
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var student1 = new Student {
ID = 1,
FirstMidName = "Allan",
LastName = "Bommer"
};
var student2 = new Student {
ID = 2,
FirstMidName = "Jerry",
LastName = "Lewis"
};
session.Save(student1);
session.Save(student2);
tx.Commit();
}
Console.ReadLine();
}
如您所见,我们已经创建了两个学生,然后调用OpenSession的Save()方法,然后调用BeginTransaction的Commit()。这是Program.cs文件中的完整实现
using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Driver;
using System;
using System.Linq;
using System.Reflection;
namespace NHibernateDemoApp {
class Program {
static void Main(string[] args) {
var cfg = new Configuration();
String Data Source = asia13797\\sqlexpress;
String Initial Catalog = NHibernateDemoDB;
String Integrated Security = True;
String Connect Timeout = 15;
String Encrypt = False;
String TrustServerCertificate = False;
String ApplicationIntent = ReadWrite;
String MultiSubnetFailover = False;
cfg.DataBaseIntegration(x = > { x.ConnectionString = "Data Source +
Initial Catalog + Integrated Security + Connect Timeout + Encrypt +
TrustServerCertificate + ApplicationIntent + MultiSubnetFailover";
x.Driver();
x.Dialect();
});
cfg.AddAssembly(Assembly.GetExecutingAssembly());
var sefact = cfg.BuildSessionFactory();
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var student1 = new Student {
ID = 1,
FirstMidName = "Allan",
LastName = "Bommer"
};
var student2 = new Student {
ID = 2,
FirstMidName = "Jerry",
LastName = "Lewis"
};
session.Save(student1);
session.Save(student2);
tx.Commit();
}
Console.ReadLine();
}
}
}
}
现在,让我们运行此应用程序,然后转到SQL Server对象资源管理器并刷新数据库。您将看到上述两个学生现在已添加到NHibernateDemoDB数据库的Student表中。
您可以看到,现在我们的学生表中有两个记录。要从表中读取这些记录,我们需要调用OpenSession的CreateCriteria() ,如以下代码所示。
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria().List();
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}",
student.ID,student.FirstMidName, student.LastName);
}
tx.Commit();
}
Console.ReadLine();
}
因此,如果您想要记录列表,那么我们只需说出Student类型的列表即可。
现在,对所有学生使用foreach ,并说在控制台上打印ID, FirstMidName和LastName 。现在,让我们再次运行该应用程序,您将在控制台窗口中看到以下输出。
1 Allan Bommer
2 Jerry Lewis
您还可以使用以下代码通过在OpenSession的Get()方法中指定ID来检索任何记录。
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria().List();
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID,
student.FirstMidName, student.LastName);
}
var stdnt = session.Get(1);
Console.WriteLine("Retrieved by ID");
Console.WriteLine("{0} \t{1} \t{2}", stdnt.ID,
stdnt.FirstMidName, stdnt.LastName);
tx.Commit();
}
Console.ReadLine();
}
现在,当您运行应用程序时,将看到以下输出。
1 Allan Bommer
2 Jerry Lewis
Retrieved by ID
1 Allan Bommer
要更新表中的记录,我们需要首先获取该特定记录,然后通过调用OpenSession的Update()方法来更新该记录,如以下代码所示。
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria().List();
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID,
student.FirstMidName, student.LastName);
}
var stdnt = session.Get(1);
Console.WriteLine("Retrieved by ID");
Console.WriteLine("{0} \t{1} \t{2}", stdnt.ID, stdnt.FirstMidName, stdnt.LastName);
Console.WriteLine("Update the last name of ID = {0}", stdnt.ID);
stdnt.LastName = "Donald";
session.Update(stdnt);
Console.WriteLine("\nFetch the complete list again\n");
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID,
student.FirstMidName, student.LastName);
}
tx.Commit();
}
Console.ReadLine();
}
现在,当您运行应用程序时,将看到以下输出。
1 Allan Bommer
2 Jerry Lewis
Retrieved by ID
1 Allan Bommer
Update the last name of ID = 1
Fetch the complete list again
1 Allan Donald
2 Jerry Lewis
如您所见,ID为1的LastName从Bommer更新为Donald。
要从表中删除任何记录,我们需要首先获取该特定记录,然后通过调用OpenSession的Delete()方法删除该记录,如以下代码所示。
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria().List();
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID,
student.FirstMidName, student.LastName);
}
var stdnt = session.Get(1);
Console.WriteLine("Retrieved by ID");
Console.WriteLine("{0} \t{1} \t{2}", stdnt.ID, stdnt.FirstMidName, stdnt.LastName);
Console.WriteLine("Delete the record which has ID = {0}", stdnt.ID);
session.Delete(stdnt);
Console.WriteLine("\nFetch the complete list again\n");
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID, student.FirstMidName,
student.LastName);
}
tx.Commit();
}
Console.ReadLine();
}
现在,当您运行应用程序时,将看到以下输出。
1 Allan Donald
2 Jerry Lewis
Retrieved by ID
1 Allan Bommer
Delete the record which has ID = 1
Fetch the complete list again
2 Jerry Lewis
如您所见,ID等于1的记录在数据库中不再可用。您还可以在SQL Server对象资源管理器中查看数据库。