There are three ways to define the database structure by Entity Framework API. They are: Attributes The DbModelBuilder API Configuration Classes Attributes We can Add some attributes for entities or proteries to configure database structures. For exa…

There are three types of relationships in database. They are: One-to-Many One-to-One Many-to-Many The One-to-Many relationship Write some codes first: class Company { public int CompanyId { get; set; } [MaxLength(50)] public string CompanyName { get;…

The default Way to handle concurrency of Entity Framework is using optimistic concurrency. When two clinets update the same entity, one of theirs data will be lost without any notify. Some times, the client want to know if his data has been saved suc…

本文涉及的相关问题,如果你的问题或需求有与下面所述相似之处,请阅读本文 [Entity Framework] Revert the database to specified migration. [Entity Framework] Re-scaffold migration file. 对于初期没有设计好Model的情况下, 已经add的migration并且已经update到db中之后可以通过下列命令达到重新编辑之前add的migration, 并且不会为你的项目新增migration文件…

Sometimes, you need to find some data in an existing context instead of the database. By befault, Entity Framework always find data in database. If you want to find data which have loaded in memory, please do it like this: Frist of all, let's insert…

Creating Entities First of all, Let's create some entities to have a test. Create a project Add following packages by NuGet EntityFramework MySql.Data.Entity (I'm just using MySql, it's not necessary) Add some codes: class Class { public int ClassId…

Sometimes, you have created two models. They have the same parent class like this: public class Person { public int PersonId { get; set; } public string PersonName { get; set; } } public class InsidePerson : Person { public string Title { get; set; }…

1.EF简介ADO.NET Entity Framework 是微软以 ADO.NET 为基础所发展出来的对象关系对应 (O/R Mapping) 解决方案.该框架曾经为.NET Framework的一部分,但version 6之后从.NET Framework分离出来. EF是微软开发的一款ORM框架.ORM框架能够自动实现Entity实体的属性与关系型数据库字段的映射,增删改查的sql脚本由ORM来自动生成,使我们编码时不用考虑数据库数据结构,而是以操作实体对象的形式来完成与数据库的交互.与…

Complex types are classes that map to a subset of columns of a table.They don't contains key. They are the Value Objects. For example, you have a entity named Company: public class Company { public int CompanyId { get; set; } public string CompanyNam…

Create a new project named MySqlTest Install following packages by right-clicking on the References folder of the project and selecting Manage NuGet Packages... EntityFramework MySql.Data MySql.data.Entity Update the app.config file Add a model and t…