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1、创建新项目并引入Entity Framework
然后就可以开始使用EF了
2、使用一对多
Users 用户类，UserDetail用户详情类：一个用户对应多个详情(仅用于测试)
public class UserDetail
{
public int DetailId { get; set; }
public string NAME { get; set; }
public int uid { get; set; }
public string remark { get; set; }
public virtual Users user { get; set; }
}
public class Users
{
public int id { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public DateTime Birth { get; set; }
public virtual ICollection<UserDetail> detail { get; set; }
}
ObjectContext类：
public class ObjectContext : DbContext
{
public ObjectContext()
: base("server=.;uid=xx;pwd=xxx;database=XXX")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Users>().HasKey(p => p.id);
modelBuilder.Entity<UserDetail>().ToTable("UserDetail");
modelBuilder.Entity<UserDetail>().HasKey(p => p.DetailId);
modelBuilder.Entity<UserDetail>().Property(p => p.NAME).HasColumnName("NAME");
modelBuilder.Entity<UserDetail>().HasRequired(p => p.user).WithMany(p => p.detail).HasForeignKey(p => p.uid);
}
public DbSet<Users> users { get; set; }
public DbSet<UserDetail> userdetail { get; set; }
}
查询方法：
public void GetAll()
{
using (ObjectContext db = new ObjectContext())
{
var users = (from a in db.users select a).ToList<Users>();
for (int i = 0; i < users.Count; i++)
{
Console.WriteLine("ID:"+users[i].id+",Name:"+users[i].Name);
foreach (var item in users[i].detail)
{
Console.WriteLine(" id:" + item.DetailId + ",NAME" + item.NAME);
}
}
}
}
删除和修改子集同时进行方法
public void Update()
{
using (ObjectContext db = new ObjectContext())
{
var users = (from a in db.users where a.id == 1 select a).First();
//删除子集
var detailitem=users.detail.Where(p=>p.DetailId==7).FirstOrDefault();
db.Entry(detailitem).State = System.Data.Entity.EntityState.Deleted;
users.detail.Remove(detailitem);
//修改子集
var detailitem2 = users.detail.Where(p=>p.DetailId==2).FirstOrDefault();
detailitem2.NAME = "这是修改后的数据";
db.Entry(detailitem2).State = System.Data.Entity.EntityState.Modified;
db.SaveChanges();
}
}
3、使用多对多
新增一个角色类 Roles
public class Roles
{
public Roles()
{
users = new HashSet<Users>();
}
public int RoleID { get; set; }
public string RoleName { get; set; }
public string Remark { get; set; }
public virtual ICollection<Users> users { get; set; }
}
修改ObjectContext类：
modelBuilder.Entity<Roles>().HasKey(p => p.RoleID);
//modelBuilder.Entity<UserRoles>().HasKey(p => p.ID);
modelBuilder.Entity<Roles>().HasMany(p => p.users).WithMany(p => p.roles).Map(
p =>
{
p.MapLeftKey("RoleId");
p.MapRightKey("UserId");
p.ToTable("UserRoles");
});
4、测试方法：
public static void AddUserRole()
{
using (ObjectContext db = new ObjectContext())
{
//添加一个用户 两个角色
var user = new Users() { Name = "Test用户1", Age = 20, Birth = DateTime.Now };
var role1 = new Roles() { RoleName = "Test角色1" };
var role2 = new Roles() { RoleName = "Test角色2" };
user.roles.Add(role1);
user.roles.Add(role2);
db.users.Add(user);
db.SaveChanges();
}
}
查询：
public static void GetAllUserRoles()
{
using (ObjectContext db = new ObjectContext())
{
var users = (from a in db.users select a).ToList<Users>();
if (users != null)
{
Console.WriteLine("User查询结果:");
foreach (var item in users)
{
Console.WriteLine("UserID：" + item.id + ",UserName：" + item.Name + ",Birth：" + item.Birth);
if (item.roles != null)
{
foreach (var role in item.roles)
{
Console.WriteLine(" RoleId：" + role.RoleID + ",RoleNmae：" + role.RoleName + ",UserId：" + item.id);
}
}
}
}
var roles = (from a in db.roles select a).ToList<Roles>();
if (roles != null)
{
Console.WriteLine("Role查询结果:");
foreach (var item in roles)
{
Console.WriteLine("RoleID：" + item.RoleID + ",RoleName：" + item.RoleName);
if (item.users != null)
{
foreach (var user in item.users)
{
Console.WriteLine(" UserID：" + user.id + ",UserName：" + user.Name + ",Birth：" + user.Birth + ",RoleID：" + item.RoleID);
}
}
}
}
}
}
然后写完测试。。。
源代码：EFDemo
