目录
1，名词概述。
2，实体数据模型EDM介绍。
3，规范函数。
4，查看Linq转换成的SQL语句。
5，数据的增删改查。
5.1，数据查询
5.2，数据插入
5.3，数据更新
5.4，数据删除
6，使用SQL语句
6.1，无结果集返回时
6.2，有结果集返回值时
6.3，调用存储过程
6.3.1，定义存储过程
6.3.2，调用存储过程
7，EF性能优化。
7.1，状态说明
7.2，优化方法
1，名词概述。
1.1，ORM：对象映射模型。
1.2，EntityClient：实体代理，用来操作EDM（实体对象模型）。
1.3，ADO.Net Provider:翻译Sql语句，用来访问数据库。
1.4，EDM（EntityDataModel）:实体数据模型。
1.5，CRUD :Create，Read，Update，Delete。
2，实体数据模型EDM介绍。
EDM包含三部分SSDL,CSDL,MSL。实现将关系数据库模型转换为实体数据模型，并将由三部分组成结构描述放在扩展名为.edmx的XML文件中。
- 添加实体数据模型
- 选择使用模式（当前使用来自数据库的EF设计器模式）
注意事项：使用Code First模型将不产生edmx文件。
- 连接数据库，添加完成后项目中自动生成edmx文件。
- 选择edmx文件右键选择打开方式，在打开方式对话框中选择XML（文本）编辑器
- 查看详细的存储结构，实体结构，映射关系等
SSDL：存储架构定义语言。负责与数据库中的数据表做实体对应（将数据表的结构与关系用xml描述）
<!-- SSDL content --><edmx:StorageModels><Schema Namespace="EFDBModel.Store" Provider="System.Data.SqlClient" ProviderManifestToken="2008" Alias="Self" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns:customannotation="http://schemas.microsoft.com/ado/2013/11/edm/customannotation" xmlns="http://schemas.microsoft.com/ado/2009/11/edm/ssdl"><EntityType Name="Admins"><Key><PropertyRef Name="LoginId" /></Key><Property Name="LoginId" Type="int" StoreGeneratedPattern="Identity" Nullable="false" /><Property Name="LoginPwd" Type="varchar" MaxLength="20" Nullable="false" /><Property Name="AdminName" Type="varchar" MaxLength="20" Nullable="false" /></EntityType><EntityType Name="ScoreList"><Key><PropertyRef Name="Id" /></Key><Property Name="Id" Type="int" StoreGeneratedPattern="Identity" Nullable="false" /><Property Name="StudentId" Type="int" Nullable="false" /><Property Name="CSharp" Type="int" /><Property Name="SQLServerDB" Type="int" /><Property Name="UpdateTime" Type="smalldatetime" Nullable="false" /></EntityType><EntityType Name="StudentClass"><Key><PropertyRef Name="ClassId" /></Key><Property Name="ClassId" Type="int" Nullable="false" /><Property Name="ClassName" Type="varchar" MaxLength="20" Nullable="false" /></EntityType><EntityType Name="Students"><Key><PropertyRef Name="StudentId" /></Key><Property Name="StudentId" Type="int" StoreGeneratedPattern="Identity" Nullable="false" /><Property Name="StudentName" Type="varchar" MaxLength="20" Nullable="false" /><Property Name="Gender" Type="char" MaxLength="2" Nullable="false" /><Property Name="Birthday" Type="smalldatetime" Nullable="false" /><Property Name="StudentIdNo" Type="numeric" Precision="18" Scale="0" Nullable="false" /><Property Name="Age" Type="int" Nullable="false" /><Property Name="PhoneNumber" Type="varchar" MaxLength="50" /><Property Name="StudentAddress" Type="varchar" MaxLength="500" /><Property Name="ClassId" Type="int" Nullable="false" /></EntityType><Association Name="fk_classId"><End Role="StudentClass" Type="Self.StudentClass" Multiplicity="1" /><End Role="Students" Type="Self.Students" Multiplicity="*" /><ReferentialConstraint><Principal Role="StudentClass"><PropertyRef Name="ClassId" /></Principal><Dependent Role="Students"><PropertyRef Name="ClassId" /></Dependent></ReferentialConstraint></Association><Association Name="fk_StudentId"><End Role="Students" Type="Self.Students" Multiplicity="1" /><End Role="ScoreList" Type="Self.ScoreList" Multiplicity="*" /><ReferentialConstraint><Principal Role="Students"><PropertyRef Name="StudentId" /></Principal><Dependent Role="ScoreList"><PropertyRef Name="StudentId" /></Dependent></ReferentialConstraint></Association><EntityContainer Name="EFDBModelStoreContainer"><EntitySet Name="Admins" EntityType="Self.Admins" Schema="dbo" store:Type="Tables" /><EntitySet Name="ScoreList" EntityType="Self.ScoreList" Schema="dbo" store:Type="Tables" /><EntitySet Name="StudentClass" EntityType="Self.StudentClass" Schema="dbo" store:Type="Tables" /><EntitySet Name="Students" EntityType="Self.Students" Schema="dbo" store:Type="Tables" /><AssociationSet Name="fk_classId" Association="Self.fk_classId"><End Role="StudentClass" EntitySet="StudentClass" /><End Role="Students" EntitySet="Students" /></AssociationSet><AssociationSet Name="fk_StudentId" Association="Self.fk_StudentId"><End Role="Students" EntitySet="Students" /><End Role="ScoreList" EntitySet="ScoreList" /></AssociationSet></EntityContainer></Schema></edmx:StorageModels>CSDL: 概念架构定义语言。概念模型对应的实体类，用实体类表示数据库中的对象。
<!-- CSDL content --><edmx:ConceptualModels><Schema Namespace="EFDBModel" Alias="Self" annotation:UseStrongSpatialTypes="false" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation" xmlns:customannotation="http://schemas.microsoft.com/ado/2013/11/edm/customannotation" xmlns="http://schemas.microsoft.com/ado/2009/11/edm"><EntityType Name="Admins"><Key><PropertyRef Name="LoginId" /></Key><Property Name="LoginId" Type="Int32" Nullable="false" annotation:StoreGeneratedPattern="Identity" /><Property Name="LoginPwd" Type="String" MaxLength="20" FixedLength="false" Unicode="false" Nullable="false" /><Property Name="AdminName" Type="String" MaxLength="20" FixedLength="false" Unicode="false" Nullable="false" /></EntityType><EntityType Name="ScoreList"><Key><PropertyRef Name="Id" /></Key><Property Name="Id" Type="Int32" Nullable="false" annotation:StoreGeneratedPattern="Identity" /><Property Name="StudentId" Type="Int32" Nullable="false" /><Property Name="CSharp" Type="Int32" /><Property Name="SQLServerDB" Type="Int32" /><Property Name="UpdateTime" Type="DateTime" Nullable="false" Precision="0" /><NavigationProperty Name="Students" Relationship="Self.fk_StudentId" FromRole="ScoreList" ToRole="Students" /></EntityType><EntityType Name="StudentClass"><Key><PropertyRef Name="ClassId" /></Key><Property Name="ClassId" Type="Int32" Nullable="false" /><Property Name="ClassName" Type="String" MaxLength="20" FixedLength="false" Unicode="false" Nullable="false" /><NavigationProperty Name="Students" Relationship="Self.fk_classId" FromRole="StudentClass" ToRole="Students" /></EntityType><EntityType Name="Students"><Key><PropertyRef Name="StudentId" /></Key><Property Name="StudentId" Type="Int32" Nullable="false" annotation:StoreGeneratedPattern="Identity" /><Property Name="StudentName" Type="String" MaxLength="20" FixedLength="false" Unicode="false" Nullable="false" /><Property Name="Gender" Type="String" MaxLength="2" FixedLength="true" Unicode="false" Nullable="false" /><Property Name="Birthday" Type="DateTime" Nullable="false" Precision="0" /><Property Name="StudentIdNo" Type="Decimal" Precision="18" Scale="0" Nullable="false" /><Property Name="Age" Type="Int32" Nullable="false" /><Property Name="PhoneNumber" Type="String" MaxLength="50" FixedLength="false" Unicode="false" /><Property Name="StudentAddress" Type="String" MaxLength="500" FixedLength="false" Unicode="false" /><Property Name="ClassId" Type="Int32" Nullable="false" /><NavigationProperty Name="ScoreList" Relationship="Self.fk_StudentId" FromRole="Students" ToRole="ScoreList" /><NavigationProperty Name="StudentClass" Relationship="Self.fk_classId" FromRole="Students" ToRole="StudentClass" /></EntityType><Association Name="fk_StudentId"><End Role="Students" Type="Self.Students" Multiplicity="1" /><End Role="ScoreList" Type="Self.ScoreList" Multiplicity="*" /><ReferentialConstraint><Principal Role="Students"><PropertyRef Name="StudentId" /></Principal><Dependent Role="ScoreList"><PropertyRef Name="StudentId" /></Dependent></ReferentialConstraint></Association><Association Name="fk_classId"><End Role="StudentClass" Type="Self.StudentClass" Multiplicity="1" /><End Role="Students" Type="Self.Students" Multiplicity="*" /><ReferentialConstraint><Principal Role="StudentClass"><PropertyRef Name="ClassId" /></Principal><Dependent Role="Students"><PropertyRef Name="ClassId" /></Dependent></ReferentialConstraint></Association><EntityContainer Name="EFDBEntities" annotation:LazyLoadingEnabled="true"><EntitySet Name="Admins" EntityType="Self.Admins" /><EntitySet Name="ScoreList" EntityType="Self.ScoreList" /><EntitySet Name="StudentClass" EntityType="Self.StudentClass" /><EntitySet Name="Students" EntityType="Self.Students" /><AssociationSet Name="fk_StudentId" Association="Self.fk_StudentId"><End Role="Students" EntitySet="Students" /><End Role="ScoreList" EntitySet="ScoreList" /></AssociationSet><AssociationSet Name="fk_classId" Association="Self.fk_classId"><End Role="StudentClass" EntitySet="StudentClass" /><End Role="Students" EntitySet="Students" /></AssociationSet></EntityContainer></Schema></edmx:ConceptualModels>MSL: 映射规范语言。 将存储模型中字段与概念模型中的属性对应。
<!-- C-S mapping content --><edmx:Mappings><Mapping Space="C-S" xmlns="http://schemas.microsoft.com/ado/2009/11/mapping/cs"><EntityContainerMapping StorageEntityContainer="EFDBModelStoreContainer" CdmEntityContainer="EFDBEntities"><EntitySetMapping Name="Admins"><EntityTypeMapping TypeName="EFDBModel.Admins"><MappingFragment StoreEntitySet="Admins"><ScalarProperty Name="LoginId" ColumnName="LoginId" /><ScalarProperty Name="LoginPwd" ColumnName="LoginPwd" /><ScalarProperty Name="AdminName" ColumnName="AdminName" /></MappingFragment></EntityTypeMapping></EntitySetMapping><EntitySetMapping Name="ScoreList"><EntityTypeMapping TypeName="EFDBModel.ScoreList"><MappingFragment StoreEntitySet="ScoreList"><ScalarProperty Name="Id" ColumnName="Id" /><ScalarProperty Name="StudentId" ColumnName="StudentId" /><ScalarProperty Name="CSharp" ColumnName="CSharp" /><ScalarProperty Name="SQLServerDB" ColumnName="SQLServerDB" /><ScalarProperty Name="UpdateTime" ColumnName="UpdateTime" /></MappingFragment></EntityTypeMapping></EntitySetMapping><EntitySetMapping Name="StudentClass"><EntityTypeMapping TypeName="EFDBModel.StudentClass"><MappingFragment StoreEntitySet="StudentClass"><ScalarProperty Name="ClassId" ColumnName="ClassId" /><ScalarProperty Name="ClassName" ColumnName="ClassName" /></MappingFragment></EntityTypeMapping></EntitySetMapping><EntitySetMapping Name="Students"><EntityTypeMapping TypeName="EFDBModel.Students"><MappingFragment StoreEntitySet="Students"><ScalarProperty Name="StudentId" ColumnName="StudentId" /><ScalarProperty Name="StudentName" ColumnName="StudentName" /><ScalarProperty Name="Gender" ColumnName="Gender" /><ScalarProperty Name="Birthday" ColumnName="Birthday" /><ScalarProperty Name="StudentIdNo" ColumnName="StudentIdNo" /><ScalarProperty Name="Age" ColumnName="Age" /><ScalarProperty Name="PhoneNumber" ColumnName="PhoneNumber" /><ScalarProperty Name="StudentAddress" ColumnName="StudentAddress" /><ScalarProperty Name="ClassId" ColumnName="ClassId" /></MappingFragment></EntityTypeMapping></EntitySetMapping></EntityContainerMapping></Mapping></edmx:Mappings></edmx:Runtime>3，规范函数。
EDM配合Linq查询语言使用，但是因为EDM中的Linq查询语言最终由Ado.net Provider编译为SQL语句，限制了EDM只能使用部分规范的方法。
- 可使用的规范函数。
System.String 静态方法 Concat(),Equals(),IsNullOrEmpty()等System.String 实例方法 Contains(),EndsWith(),StartsWith(),Replace()等DataTime 静态方法DataTime 实例方法Math静态方法Guid静态方法例如：
context.Students.Where(t => t.StudentName.StartsWith("张"));
//被provider翻译为：
SELECT [Extent1].[StudentId] AS [StudentId], [Extent1].[StudentName] AS [StudentName], [Extent1].[Gender] AS [Gender], [Extent1].[Birthday] AS [Birthday], [Extent1].[StudentIdNo] AS [StudentIdNo], [Extent1].[Age] AS [Age], [Extent1].[PhoneNumber] AS [PhoneNumber], [Extent1].[StudentAddress] AS [StudentAddress], [Extent1].[ClassId] AS [ClassId]FROM [dbo].[Students] AS [Extent1]WHERE [Extent1].[StudentName] LIKE '张%'//如果是使用非规范函数的正则表达式，则抛出异常：
//其他信息: LINQ to Entities 不识别方法“Boolean IsMatch(System.String, System.String)”，因//此该方法无法转换为存储表达式。），因无法转译为SQL语句
context.Students.Where(t => System.Text.RegularExpressions.Regex.IsMatch(t.StudentName, "^张.*"));//抛出异常4，查看Linq转换成的SQL语句。
查询表达式.ToString()即可查看转换SQL语句。需要注意的是Linq查询是延迟查询，即使用时才进行查询。
5，数据的增删改查。
使用的数据
5.1，数据查询
MyDbContext context = new MyDbContext();
//普通查询
var result = context.Students.Where(s => s.StudentId > 100004);
Students ss= context.Students.Find(100004);//多表联合查询
var arr= from a in context.ScoreList where a.StudentId>=100004select new{a.StudentId,a.SQLServerDB,a.Students.StudentName,a.Students.StudentClass.ClassName};
5.2，数据插入
MyDbContext context = new MyDbContext();
//添加方式Students s = new Students{Age = 23,Birthday = DateTime.Parse("2001/4/23"),Gender = "女",PhoneNumber = "1234567",StudentAddress = "湖北武汉",StudentIdNo = 123456789987654321,StudentName = "李欣",ClassId = context.StudentClass.FirstOrDefault(t => t.ClassName.Equals("网络1班")).ClassId};context.Students.Add(s);context.SaveChanges();//方式2
s.StudentIdNo = 123456789987654322;context.Entry(s).State = System.Data.Entity.EntityState.Added;context.SaveChanges();
//方式3Students stu = new Students{StudentId = 100010,Age = 20,Birthday = DateTime.Parse("1998/7/23"),Gender = "女",PhoneNumber = "13232224242",StudentIdNo = 111111110111111118,StudentAddress = "广东东莞",StudentName = "张三",};//注意这里无需指明classId//这里获取StudentClass对象，该对象包含了classId同时也包含了导航属性students（导航属性students中的Studentid均相同，主外键一对多的关系）
(from c in context.StudentClass where c.ClassName.Equals("计算机2班") select c).FirstOrDefault().Students.Add(stu);
context.SaveChanges();5.3，数据更新
//方式1
Students stu = context.Students.Find(100014);
stu.StudentName = "李2新";
context.SaveChanges();
//方式2
Students stu2 = new Students
{Age = 23,Birthday = DateTime.Parse("2001/4/23"),Gender = "女",PhoneNumber = "1234567",StudentAddress = "湖北武汉",StudentIdNo = 123456789987654323,StudentName = "李欣",ClassId = context.StudentClass.FirstOrDefault(t => t.ClassName.Equals("网络1班")).ClassId,
StudentId = 100015
};context.Entry(stu2).State = System.Data.Entity.EntityState.Modified;
context.SaveChanges();5.4，数据删除
//方法1，查询出对象再删除Students stu1 = context.Students.Find(100014);context.Students.Remove(stu1);context.SaveChanges();
//方法2，创建对象直接删除Students stu2 = new Students { StudentId = 100013 };context.Entry(stu2).State = System.Data.Entity.EntityState.Deleted;context.SaveChanges();
//方法3，创建对象附加后再删除Students stu3 = new Students { StudentId = 100011 };context.Students.Attach(stu3);context.Students.Remove(stu3);context.SaveChanges();
//方法4Students stu3 = new Students { StudentId = 100011 };context.Entry(stu3).State = System.Data.Entity.EntityState.Unchanged;context.Students.Remove(stu3);context.SaveChanges();6，使用SQL语句
6.1，无结果集返回时
//增加string sqlcmd = "insert into StudentClass (ClassId,ClassName) values (7,\'软件10班\')";//删除string sqlcmd2 = "delete from StudentClass where ClassId>=7";context.Database.ExecuteSqlCommand(sqlcmd);6.2，有结果集返回值时
var arr = context.Database.SqlQuery<StudentClass>("select * from StudentClass");foreach (var item in arr){Console.WriteLine(item.ClassId + "\t" + item.ClassName);}6.3，调用存储过程
6.3.1,定义存储过程
--存储过程1if exists(select * from sysobjects where name='ups_procUpate')drop proc ups_procUpategocreate proc ups_procUpate@studentName nvarchar(50),@id int = 100004asupdate Students set StudentName=@studentName where StudentId=@idgo--存储过程2 if exists(select * from sysobjects where name ='ups_procRead')drop proc ups_procReadgocreate proc ups_procRead @id intasselect * from Students where StudentId>=@idgo6.3.2，调用存储过程
//调用存储过程context.Database.ExecuteSqlCommand("exec ups_procUpate '猪八戒',100005");
//调用带参数的存储过程System.Data.SqlClient.SqlParameter[] paras = new System.Data.SqlClient.SqlParameter[]{new System.Data.SqlClient.SqlParameter("@studentName","牛魔王"),new System.Data.SqlClient.SqlParameter("@id",100006)};context.Database.ExecuteSqlCommand("exec ups_procUpate @studentName,@id ", paras);
//调用具有查询结果的存储过程var collect = context.Database.SqlQuery<Students>("exec ups_procRead 100004");foreach (var item in collect){Console.WriteLine(item.StudentId + "\t" + item.StudentName);}7，EF性能优化。
7.1，状态说明
EntityState
状态 整数值 说明 具备该状态的对象Detached 1 对象存在但未被跟踪 新创建的对象UNchanged 2 对象尚未经过修改 使用DbContext读取的对象使用Attach()方法添加的对象执行SaveChange（）后的对象Added 4 对象为新对象，并已添加 使用Add（）方法添加的对象到上下文中Deleted 8 对象已从上下文中删除 使用Remove()移除对象 7.2，优化方法
使用AsNoTracing()方法
不进行状态跟踪添加AsNoTracing（）方法后，对象将不被状态管理，查询性能提高返回的实体将不再DbContext中缓存只适合纯粹的查询操作。
//默认状态跟踪Students stu = (from a in context.Students where a.StudentId.Equals(100004) select a).FirstOrDefault();Console.WriteLine("该Student状态:{0}", context.Entry(stu).State);//不进行状态跟踪Students stu2 = context.Students.AsNoTracking().FirstOrDefault(a => a.StudentId.Equals(100004));Console.WriteLine("该Student状态:{0}", context.Entry(stu2).State);禁用自动跟踪（默认开启）DbContext.Configuration.AutoDetectChangesEnabled = false;
关闭前，当执行Add()操作时耗费大量的性能，导致DbContext遍历所有缓存的Entity，比较原始值和当前值，非常耗时。
关闭后使用Add()告知DbContext变化即可，如果是删除使用Remove()方法，以及通过State属性告知变化。
适合于大批量操作数据（添加，删除，修改）
System.Diagnostics.Stopwatch watch = new System.Diagnostics.Stopwatch();Console.WriteLine("启用状态自动跟踪");context.Configuration.AutoDetectChangesEnabled = true;for (int i = 17; i < 27; i++){Console.WriteLine("第{0}次", i);StudentClass sc = new StudentClass { ClassName = $"网络{i}班", ClassId = i };Console.WriteLine("\t添加之前状态：{0}", context.Entry(sc).State);context.StudentClass.Add(sc);Console.WriteLine("\t添加之后状态：{0}", context.Entry(sc).State);}context.SaveChanges();Console.WriteLine("耗时：{0}", watch.Elapsed);Console.WriteLine("禁用状态自动跟踪");context.Configuration.AutoDetectChangesEnabled = false;watch.Restart();for (int i = 27; i < 37; i++){Console.WriteLine("第{0}次", i);StudentClass sc = new StudentClass { ClassName = $"网络{i}班", ClassId = i };Console.WriteLine("\t添加之前状态：{0}", context.Entry(sc).State);context.StudentClass.Add(sc);Console.WriteLine("\t添加之后状态：{0}", context.Entry(sc).State);}context.SaveChanges();Console.WriteLine("耗时：{0}", watch.Elapsed);
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