說明：本篇重點說明MiniAPI引入EntityFramework，EF的使用不是本篇的重點

本篇是在MiniAPI中使用EntityFramework，所以先奉上創(chuàng)建數(shù)據(jù)的腳本，數(shù)據(jù)庫是SQL Server，可能版本不同，會有一些問題，可以自行調(diào)整，這個腳本是基于SQL Server2019的。

USE [Exam] GO /****** Object: Table [dbo].[Answers] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Answers]([ID] [int] IDENTITY(1,1) NOT NULL,[Sequre] [nvarchar](8) NOT NULL,[Answer] [nvarchar](200) NOT NULL,[IsTrue] [bit] NOT NULL,[QuestionID] [int] NOT NULL,CONSTRAINT [PK_Answers] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[ExamPaperQuestions] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[ExamPaperQuestions]([ExamPaperID] [int] NOT NULL,[QuestionID] [int] NOT NULL,CONSTRAINT [PK_ExamPaperQuestions_1] PRIMARY KEY CLUSTERED ([ExamPaperID] ASC,[QuestionID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[ExamPapers] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[ExamPapers]([ID] [int] IDENTITY(1,1) NOT NULL,[Title] [nvarchar](200) NOT NULL,[Memo] [nvarchar](1000) NULL,[CreateTime] [datetime2](7) NOT NULL,CONSTRAINT [PK_ExamPapers] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[Questions] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Questions]([ID] [int] IDENTITY(1,1) NOT NULL,[Question] [nvarchar](300) NOT NULL,[Score] [float] NOT NULL,[QuestionTypeID] [int] NOT NULL,[SujectTypeID] [int] NOT NULL,CONSTRAINT [PK_Questions] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[QuestionTypes] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[QuestionTypes]([ID] [int] IDENTITY(1,1) NOT NULL,[TypeName] [nvarchar](50) NOT NULL,CONSTRAINT [PK_QuestionTypes] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[SubjectTypes] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[SubjectTypes]([ID] [int] IDENTITY(1,1) NOT NULL,[TypeName] [nvarchar](50) NOT NULL,CONSTRAINT [PK_SubjectTypes] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[UserExamAnswers] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[UserExamAnswers]([ID] [int] IDENTITY(1,1) NOT NULL,[UserExamID] [int] NOT NULL,[AnswerID] [int] NOT NULL,[CreateTime] [datetime] NOT NULL,CONSTRAINT [PK_UserExamAnswers] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[UserExams] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[UserExams]([ID] [int] IDENTITY(1,1) NOT NULL,[UserID] [int] NOT NULL,[ExamPapgerID] [int] NOT NULL,[BeginTime] [datetime] NOT NULL,[EndTime] [datetime] NOT NULL,CONSTRAINT [PK_UserExams] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO /****** Object: Table [dbo].[Users] Script Date: 2022/1/22 10:01:19 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Users]([ID] [int] IDENTITY(1,1) NOT NULL,[UserName] [nvarchar](50) NOT NULL,[Password] [nvarchar](50) NOT NULL,[Salt] [nvarchar](50) NOT NULL,[Name] [nvarchar](50) NOT NULL,[Tel] [varchar](11) NULL,CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED ([ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET IDENTITY_INSERT [dbo].[Answers] ON INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (1, N'A', N'循環(huán)', 0, 1) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (2, N'B', N'指針 ', 1, 1) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (3, N'C', N'判斷 ', 0, 1) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (4, N'D', N'數(shù)組', 0, 1) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (5, N'A', N'只讀', 1, 2) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (6, N'B', N'只寫', 0, 2) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (7, N'C', N'可讀寫', 0, 2) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (8, N'D', N'不可讀不可寫', 0, 2) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (9, N'A', N'break', 1, 3) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (10, N'B', N'goto', 0, 3) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (11, N'C', N'return ', 0, 3) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (12, N'D', N'continue', 0, 3) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (13, N'A', N'class', 0, 4) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (14, N'B', N'using', 1, 4) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (16, N'D', N'this', 0, 4) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (17, N'A', N'click', 0, 5) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (18, N'B', N'catch', 0, 5) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (19, N'C', N'try', 1, 5) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (20, N'D', N'show', 0, 5) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (21, N'A', N'該復(fù)選框被選中', 1, 6) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (22, N'B', N'該復(fù)選框不被選中', 0, 6) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (23, N'C', N'不顯示該復(fù)選框的文本信息', 0, 6) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (24, N'D', N'顯示該復(fù)選框的文本信息', 0, 6) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (25, N'A', N'System', 0, 7) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (26, N'B', N'System.Data', 0, 7) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (27, N'C', N'System.Data.OleDb', 0, 7) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (28, N'D', N'System.Data.SqlClient', 1, 7) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (29, N'A', N'FileStream類 ', 1, 8) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (30, N'B', N'StreamReade', 0, 8) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (31, N'C', N'BinaryWriter類', 0, 8) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (32, N'D', N'BinaryReader', 0, 8) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (33, N'A', N'輸入、編譯、運行', 1, 9) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (34, N'B', N'編譯、連接、運行', 0, 9) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (35, N'C', N'輸入、運行、編輯', 0, 9) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (36, N'D', N'編輯、編譯、連接', 0, 9) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (37, N'A', N'int轉(zhuǎn)換成short', 0, 10) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (38, N'B', N'short轉(zhuǎn)換成long', 0, 10) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (39, N'C', N'char轉(zhuǎn)換成int', 0, 10) INSERT [dbo].[Answers] ([ID], [Sequre], [Answer], [IsTrue], [QuestionID]) VALUES (40, N'D', N'bytes轉(zhuǎn)換成float', 1, 10) SET IDENTITY_INSERT [dbo].[Answers] OFF GO INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 1) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 2) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 3) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 4) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 5) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 6) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 7) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 8) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 9) INSERT [dbo].[ExamPaperQuestions] ([ExamPaperID], [QuestionID]) VALUES (1, 10) GO SET IDENTITY_INSERT [dbo].[ExamPapers] ON INSERT [dbo].[ExamPapers] ([ID], [Title], [Memo], [CreateTime]) VALUES (1, N'C#初級試題一（2021）', N'2021年10月生成', CAST(N'2021-12-13T22:26:44.0129362' AS DateTime2)) INSERT [dbo].[ExamPapers] ([ID], [Title], [Memo], [CreateTime]) VALUES (2, N'C#初級試題二（2021）', N'2021年11月生成', CAST(N'2021-12-13T22:26:44.0129382' AS DateTime2)) INSERT [dbo].[ExamPapers] ([ID], [Title], [Memo], [CreateTime]) VALUES (3, N'C#初級試題三（2021）', N'2021年12月生成', CAST(N'2021-12-13T22:26:44.0129383' AS DateTime2)) SET IDENTITY_INSERT [dbo].[ExamPapers] OFF GO SET IDENTITY_INSERT [dbo].[Questions] ON INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (1, N'C#語言取消了（ ）語法。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (2, N'以下類MyClass的屬性count屬于（ ）屬性。 class MyClass {int i;int count { get { return i; } } }', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (3, N'（ ）語句只能在循環(huán)語句的循環(huán)體語句序列中使用。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (4, N'在C#應(yīng)用程序中，一般在程序的開頭使用關(guān)鍵字（ ）來引入命名空間。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (5, N'異常處理使用時，一般將可能出現(xiàn)異常的語句放在（ ）代碼塊中。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (6, N'WinForms程序中，如果復(fù)選框控件的 Checked屬性值設(shè)置為 True，表示（ ）。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (7, N'在ADO.NET中，SqlConnection 類所在的命名空間是（ ）。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (8, N'下面哪個類是用來以字節(jié)格式讀寫文件（ ）。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (9, N'C#程序從上機到得到結(jié)果的幾個操作步驟依次是( )。', 10, 1, 1) INSERT [dbo].[Questions] ([ID], [Question], [Score], [QuestionTypeID], [SujectTypeID]) VALUES (10, N'下面的轉(zhuǎn)換中不是隱式轉(zhuǎn)換的是（ ）。', 10, 1, 1) SET IDENTITY_INSERT [dbo].[Questions] OFF GO SET IDENTITY_INSERT [dbo].[QuestionTypes] ON INSERT [dbo].[QuestionTypes] ([ID], [TypeName]) VALUES (1, N'單項選擇題') INSERT [dbo].[QuestionTypes] ([ID], [TypeName]) VALUES (2, N'多項選擇題') INSERT [dbo].[QuestionTypes] ([ID], [TypeName]) VALUES (3, N'判斷題') SET IDENTITY_INSERT [dbo].[QuestionTypes] OFF GO SET IDENTITY_INSERT [dbo].[SubjectTypes] ON INSERT [dbo].[SubjectTypes] ([ID], [TypeName]) VALUES (1, N'C Sharp(C#)') INSERT [dbo].[SubjectTypes] ([ID], [TypeName]) VALUES (2, N'SQL Server') SET IDENTITY_INSERT [dbo].[SubjectTypes] OFF GO SET IDENTITY_INSERT [dbo].[UserExams] ON INSERT [dbo].[UserExams] ([ID], [UserID], [ExamPapgerID], [BeginTime], [EndTime]) VALUES (1, 1, 1, CAST(N'2021-12-01T00:00:00.000' AS DateTime), CAST(N'2022-12-01T00:00:00.000' AS DateTime)) SET IDENTITY_INSERT [dbo].[UserExams] OFF GO SET IDENTITY_INSERT [dbo].[Users] ON INSERT [dbo].[Users] ([ID], [UserName], [Password], [Salt], [Name], [Tel]) VALUES (1, N'zhangsan', N'@f232fd(feef', N'sfw32==', N'張三', N'13456879562') INSERT [dbo].[Users] ([ID], [UserName], [Password], [Salt], [Name], [Tel]) VALUES (2, N'lisi', N'@22ewfd(feef', N'42syt==', N'李四', N'13456879562')SET IDENTITY_INSERT [dbo].[Users] OFF GO ALTER TABLE [dbo].[ExamPapers] ADD DEFAULT (getdate()) FOR [CreateTime] GO ALTER TABLE [dbo].[UserExamAnswers] ADD DEFAULT (getdate()) FOR [CreateTime] GO ALTER TABLE [dbo].[Answers] WITH CHECK ADD CONSTRAINT [FK_Answers_Questions] FOREIGN KEY([QuestionID]) REFERENCES [dbo].[Questions] ([ID]) GO ALTER TABLE [dbo].[Answers] CHECK CONSTRAINT [FK_Answers_Questions] GO ALTER TABLE [dbo].[ExamPaperQuestions] WITH CHECK ADD CONSTRAINT [FK_ExamPaperQuestions_ExamPapers] FOREIGN KEY([ExamPaperID]) REFERENCES [dbo].[ExamPapers] ([ID]) GO ALTER TABLE [dbo].[ExamPaperQuestions] CHECK CONSTRAINT [FK_ExamPaperQuestions_ExamPapers] GO ALTER TABLE [dbo].[ExamPaperQuestions] WITH CHECK ADD CONSTRAINT [FK_ExamPaperQuestions_Questions] FOREIGN KEY([QuestionID]) REFERENCES [dbo].[Questions] ([ID]) GO ALTER TABLE [dbo].[ExamPaperQuestions] CHECK CONSTRAINT [FK_ExamPaperQuestions_Questions] GO ALTER TABLE [dbo].[Questions] WITH CHECK ADD CONSTRAINT [FK_Questions_QuestionTypes] FOREIGN KEY([QuestionTypeID]) REFERENCES [dbo].[QuestionTypes] ([ID]) GO ALTER TABLE [dbo].[Questions] CHECK CONSTRAINT [FK_Questions_QuestionTypes] GO ALTER TABLE [dbo].[Questions] WITH CHECK ADD CONSTRAINT [FK_Questions_SubjectTypes] FOREIGN KEY([SujectTypeID]) REFERENCES [dbo].[SubjectTypes] ([ID]) GO ALTER TABLE [dbo].[Questions] CHECK CONSTRAINT [FK_Questions_SubjectTypes] GO ALTER TABLE [dbo].[UserExamAnswers] WITH CHECK ADD CONSTRAINT [FK_UserExamAnswers_Answers] FOREIGN KEY([AnswerID]) REFERENCES [dbo].[Answers] ([ID]) GO ALTER TABLE [dbo].[UserExamAnswers] CHECK CONSTRAINT [FK_UserExamAnswers_Answers] GO ALTER TABLE [dbo].[UserExamAnswers] WITH CHECK ADD CONSTRAINT [FK_UserExamAnswers_UserExams] FOREIGN KEY([UserExamID]) REFERENCES [dbo].[UserExams] ([ID]) GO ALTER TABLE [dbo].[UserExamAnswers] CHECK CONSTRAINT [FK_UserExamAnswers_UserExams] GO ALTER TABLE [dbo].[UserExams] WITH CHECK ADD CONSTRAINT [FK_UserExams_ExamPapers] FOREIGN KEY([ExamPapgerID]) REFERENCES [dbo].[ExamPapers] ([ID]) GO ALTER TABLE [dbo].[UserExams] CHECK CONSTRAINT [FK_UserExams_ExamPapers] GO ALTER TABLE [dbo].[UserExams] WITH CHECK ADD CONSTRAINT [FK_UserExams_Users] FOREIGN KEY([UserID]) REFERENCES [dbo].[Users] ([ID]) GO ALTER TABLE [dbo].[UserExams] CHECK CONSTRAINT [FK_UserExams_Users] GO

有了數(shù)據(jù)庫后，接下來開始在Mini API項目中引入EntityFramework，首選安裝dotnet-ef的tool：

dotnet?tool?install?--global?dotnet-ef

再在項目中引入nuget包? Microsoft.EntityFrameworkCore.Design和Microsoft.EntityFrameworkCore.SqlServer

這時就可以從數(shù)據(jù)生成EF的實體類了：

dotnet?ef?dbcontext?scaffold?"server=.;database=Exam;uid=sa;pwd=sa;"?Microsoft.EntityFrameworkCore.SqlServer?-o?Models

對生成的EF實體類進(jìn)行整理，因為在導(dǎo)出實體類時，我們給了他一個連接字符串，所以在生成的實體類中是有這個連字符串的，打開ExamContext.cs，刪除選中OnConfiguring這個方法。

在appsetings.json中配置連接字符串

"ConnectionStrings": {"ExamDatabase": "server=.;database=Exam;uid=sa;pwd=sa;"}

引入EF用AddDbContext，參數(shù)Options決定有什么類型的數(shù)據(jù)庫，和數(shù)據(jù)庫連接字符串。然后在MapGet中從服務(wù)容器中取到ExamContext使用就可以。

using MiniDemo04.Models; using Microsoft.EntityFrameworkCore; using System.Text.Json.Serialization;var builder = WebApplication.CreateBuilder(args);builder.Services.AddDbContext<ExamContext>(options =>options.UseSqlServer(builder.Configuration.GetConnectionString("ExamDatabase")));var app = builder.Build();app.MapGet("/exampaper/{id}", async (ExamContext exam, int id) =>{return Results.Json(await exam.ExamPapers.Include(paper => paper.Questions).ThenInclude(question => question.Answers).Include(paper => paper.Questions).ThenInclude(question => question.QuestionType) .Select(paper => new { paper.Id, paper.Title, paper.CreateTime, Scores = paper.Questions.Sum(s => s.Score), Count = paper.Questions.Count, Questions = paper.Questions.Select(question => new { Question = $"{question.Id}、{question.Question1}({question.Score}分 {question.QuestionType.TypeName})", Answers = question.Answers.Select(answer => new { answer.Sequre, Answer = answer.Answer1 }) }) }).FirstOrDefaultAsync(s => s.Id == id), new System.Text.Json.JsonSerializerOptions { ReferenceHandler = ReferenceHandler.IgnoreCycles });});app.Run();

運行結(jié)果：

總結(jié)

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