C# ORM學習筆記：Dapper基本用法

本文轉載自查看原文 2020-04-29 14:49 1552 115-C#-ORM

一、基礎知識

1.1、Dapper簡介

Dapper是.NET下的一個micro ORM，它和Entity Framework或NHibnate不同，屬於輕量級並且是半自動的（實體類都要自己寫）。假如你喜歡原生的Sql語句，又喜歡ORM的簡單，那你一定會喜歡上Dapper這款ORM。

1.2、Dapper優點

1）輕量。只有一個文件（SqlMapper.cs）。

2）速度快。Dapper的速度接近於IDataReader，取列表的數據超過了DataTable。

3）支持多種數據庫。包括SQLite、SqlCe、Firebird、Oracle、MySQL、PostgreSQL、SQL Server。

4）可以映射一對一、一對多、多對多等多種關系。

5）性能高。通過Emit反射IDataReader的序列隊列，來快速地得到和產生對象。

1.3、Dapper安裝

此處使用Dapper擴展庫Dapper.SimpleCRUD，它也會默認安裝Dapper（依賴項）：

項目右鍵->管理 NuGet 程序包->Dapper.SimpleCRUD。

二、數據准備

2.1、數據表

在SQL Server中創建4個數據表，分別是：Student（學生表）、Teacher（教師表）、Course（課程表）、Record（成績表）。

--學生表
CREATE TABLE [dbo].[Student](
    [StudentID] [INT] IDENTITY(1,1) NOT NULL,
    [Name] [NVARCHAR](50) NULL,
    [Age] [SMALLINT] NULL,
    [Gender] [NVARCHAR](10) NULL,
 CONSTRAINT [PK_Student] PRIMARY KEY CLUSTERED 
(
    [StudentID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--教師表
CREATE TABLE [dbo].[Teacher](
    [TeacherID] [INT] IDENTITY(1,1) NOT NULL,
    [Name] [NVARCHAR](50) NULL,
 CONSTRAINT [PK_Teacher] PRIMARY KEY CLUSTERED 
(
    [TeacherID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--課程表
CREATE TABLE [dbo].[Course](
    [CourseID] [int] IDENTITY(1,1) NOT NULL,
    [Name] [nvarchar](50) NULL,
    [TeacherID] [int] NULL,
 CONSTRAINT [PK_Course] PRIMARY KEY CLUSTERED 
(
    [CourseID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--成績表
CREATE TABLE [dbo].[Record](
    [StudentID] [INT] NOT NULL,
    [CourseID] [INT] NOT NULL,
    [Score] [NUMERIC](8, 2) NULL,
 CONSTRAINT [PK_Score] PRIMARY KEY CLUSTERED 
(
    [StudentID] ASC,
    [CourseID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

--學生表數據插入
INSERT INTO Student (Name,Age,Gender)
SELECT N'劉一',18,N'female'
UNION
SELECT N'陳二',19,N'female'
UNION
SELECT N'張三',18,N'male'
UNION
SELECT N'李四',19,N'male'
UNION
SELECT N'王五',18,N'male'
UNION
SELECT N'趙六',19,N'male'
UNION
SELECT N'孫七',19,N'female'

--教師表數據插入
INSERT INTO Teacher (Name)
SELECT N'周八'
UNION
SELECT N'吳九'
UNION
SELECT N'鄭十'

--課程表數據插入
INSERT INTO Course (Name,TeacherID)
SELECT N'離散數學',1
UNION
SELECT N'程序設計',2
UNION
SELECT N'數據結構',3

--成績表數據插入
INSERT INTO Record (StudentID,CourseID,Score )
SELECT 1,1,90
UNION
SELECT 2,1,91
UNION
SELECT 3,1,89
UNION
SELECT 4,1,75
UNION
SELECT 5,1,96
UNION
SELECT 6,1,78
UNION
SELECT 7,1,83
UNION
SELECT 1,2,86
UNION
SELECT 2,2,92
UNION
SELECT 3,2,77
UNION
SELECT 4,2,71
UNION
SELECT 5,2,66
UNION
SELECT 6,2,87
UNION
SELECT 7,2,93
UNION
SELECT 1,3,81
UNION
SELECT 2,3,90
UNION
SELECT 3,3,88
UNION
SELECT 4,3,82
UNION
SELECT 5,3,93
UNION
SELECT 6,3,91
UNION
SELECT 7,3,84

View Code

2.2、實體類

Dapper的實體映射：

1）屬性不編輯，用[Editable(false)]這個特性標記，默認是true。

2）類名到表名的映射，用[Table("TableName")]特性，TableName對應物理數據表名稱。

3）主鍵映射，如果您的實體類中有Id屬性，Dapper會默認此屬性為主鍵，否則要為作為主鍵的屬性添加[Key]特性。

由上可知，如Student表，其實體類應該生成下面這個樣子：

using System;
using System.Collections.Generic;
using System.Text;
using Dapper;

namespace LinkTo.Test.ConsoleDapper
{
    [Table("Student")]
    [Serializable]
    public class Student
    {
        [Key]
        public int? StudentID {get; set;}

        public string Name {get; set;}

        public short? Age {get; set;}

        public string Gender {get; set;}
    }
}

View Code

2.3、使用T4模板生成實體類

2.3.1、T4Code文件夾的文本模板

<#@ assembly name="System.Core" #>
<#@ assembly name="System.Data" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Data"#>
<#@ import namespace="System.Data.SqlClient"#>
<#+
    #region T4Code
    /// <summary>
    /// 數據庫架構接口
    /// </summary>
    public interface IDBSchema : IDisposable
    {
        List<string> GetTableList();
        DataTable GetTableMetadata(string tableName);
    }

    /// <summary>
    /// 數據庫架構工廠
    /// </summary>
    public class DBSchemaFactory
    {
        static readonly string DatabaseType = "SqlServer";
        public static IDBSchema GetDBSchema()
        {
            IDBSchema dbSchema;
            switch (DatabaseType) 
            {
                case "SqlServer":
                    {
                        dbSchema =new SqlServerSchema();
                        break;
                    }
                default: 
                    {
                        throw new ArgumentException("The input argument of DatabaseType is invalid.");
                    }
            }
            return dbSchema;
        }
    }

    /// <summary>
    /// SqlServer
    /// </summary>
    public class SqlServerSchema : IDBSchema
    {
        public string ConnectionString = "Server=.;Database=Test;Uid=sa;Pwd=********;";
        public SqlConnection conn;

        public SqlServerSchema()
        {
            conn = new SqlConnection(ConnectionString);
            conn.Open();
        }

        public List<string> GetTableList()
        {
            List<string> list = new List<string>();
            string commandText = "SELECT NAME TABLE_NAME FROM SYSOBJECTS WHERE XTYPE='U' ORDER BY NAME";

            using(SqlCommand cmd = new SqlCommand(commandText, conn))
            {
                using (SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection))
                {
                    while (dr.Read())
                    {
                        list.Add(dr["TABLE_NAME"].ToString());
                    }
                }
            }

            return list;
        }
        
        public DataTable GetTableMetadata(string tableName)
        {
            string commandText=string.Format
                (
                    "SELECT A.NAME TABLE_NAME,B.NAME FIELD_NAME,C.NAME DATATYPE,ISNULL(B.PREC,0) LENGTH, "+
                        "CONVERT(BIT,CASE WHEN NOT F.ID IS NULL THEN 1 ELSE 0 END) ISKEY, "+
                        "CONVERT(BIT,CASE WHEN COLUMNPROPERTY(B.ID,B.NAME,'ISIDENTITY') = 1 THEN 1 ELSE 0 END) AS ISIDENTITY, "+
                        "CONVERT(BIT,B.ISNULLABLE) ISNULLABLE "+
                    "FROM SYSOBJECTS A INNER JOIN SYSCOLUMNS B ON A.ID=B.ID INNER JOIN SYSTYPES C ON B.XTYPE=C.XUSERTYPE "+
                        "LEFT JOIN SYSOBJECTS D ON B.ID=D.PARENT_OBJ AND D.XTYPE='PK' "+
                        "LEFT JOIN SYSINDEXES E ON B.ID=E.ID AND D.NAME=E.NAME "+
                        "LEFT JOIN SYSINDEXKEYS F ON B.ID=F.ID AND B.COLID=F.COLID AND E.INDID=F.INDID "+
                    "WHERE A.XTYPE='U' AND A.NAME='{0}' "+
                    "ORDER BY A.NAME,B.COLORDER", tableName
                );

            using(SqlCommand cmd = new SqlCommand(commandText, conn))
            {
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                DataSet ds = new DataSet();
                da.Fill(ds,"Schema");
                return ds.Tables[0];
            }
        }

        public void Dispose()
        {
            if (conn != null)
            {
                conn.Close();
            }
        }
    }
    #endregion
#>

DBSchema.ttinclude

<#@ assembly name="System.Core" #>
<#@ assembly name="System.Data" #>
<#@ assembly name="EnvDTE" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Data"#>
<#@ import namespace="System.IO"#>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating"#>

<#+
// T4 Template Block manager for handling multiple file outputs more easily.
// Copyright (c) Microsoft Corporation.All rights reserved.
// This source code is made available under the terms of the Microsoft Public License (MS-PL)

// Manager class records the various blocks so it can split them up
class Manager
{
    public struct Block
    {
        public string Name;
        public int Start, Length;
    }

    public List<Block> blocks = new List<Block>();
    public Block currentBlock;
    public Block footerBlock = new Block();
    public Block headerBlock = new Block();
    public ITextTemplatingEngineHost host;
    public ManagementStrategy strategy;
    public StringBuilder template;
    public string OutputPath { get; set; }

    public Manager(ITextTemplatingEngineHost host, StringBuilder template, bool commonHeader)
    {
        this.host = host;
        this.template = template;
        OutputPath = string.Empty;
        strategy = ManagementStrategy.Create(host);
    }

    public void StartBlock(string name)
    {
        currentBlock = new Block { Name = name, Start = template.Length };
    }

    public void StartFooter()
    {
        footerBlock.Start = template.Length;
    }

    public void EndFooter()
    {
        footerBlock.Length = template.Length - footerBlock.Start;
    }

    public void StartHeader()
    {
        headerBlock.Start = template.Length;
    }

    public void EndHeader()
    {
        headerBlock.Length = template.Length - headerBlock.Start;
    }    

    public void EndBlock()
    {
        currentBlock.Length = template.Length - currentBlock.Start;
        blocks.Add(currentBlock);
    }

    public void Process(bool split)
    {
        string header = template.ToString(headerBlock.Start, headerBlock.Length);
        string footer = template.ToString(footerBlock.Start, footerBlock.Length);
        blocks.Reverse();
        foreach(Block block in blocks) {
            string fileName = Path.Combine(OutputPath, block.Name);
            if (split) {
                string content = header + template.ToString(block.Start, block.Length) + footer;
                strategy.CreateFile(fileName, content);
                template.Remove(block.Start, block.Length);
            } else {
                strategy.DeleteFile(fileName);
            }
        }
    }
}

class ManagementStrategy
{
    internal static ManagementStrategy Create(ITextTemplatingEngineHost host)
    {
        return (host is IServiceProvider) ? new VSManagementStrategy(host) : new ManagementStrategy(host);
    }

    internal ManagementStrategy(ITextTemplatingEngineHost host) { }

    internal virtual void CreateFile(string fileName, string content)
    {
        File.WriteAllText(fileName, content);
    }

    internal virtual void DeleteFile(string fileName)
    {
        if (File.Exists(fileName))
            File.Delete(fileName);
    }
}

class VSManagementStrategy : ManagementStrategy
{
    private EnvDTE.ProjectItem templateProjectItem;

    internal VSManagementStrategy(ITextTemplatingEngineHost host) : base(host)
    {
        IServiceProvider hostServiceProvider = (IServiceProvider)host;
        if (hostServiceProvider == null)
            throw new ArgumentNullException("Could not obtain hostServiceProvider");

        EnvDTE.DTE dte = (EnvDTE.DTE)hostServiceProvider.GetService(typeof(EnvDTE.DTE));
        if (dte == null)
            throw new ArgumentNullException("Could not obtain DTE from host");

        templateProjectItem = dte.Solution.FindProjectItem(host.TemplateFile);
    }

    internal override void CreateFile(string fileName, string content)
    {
        base.CreateFile(fileName, content);
        ((EventHandler)delegate { templateProjectItem.ProjectItems.AddFromFile(fileName); }).BeginInvoke(null, null, null, null);
    }

    internal override void DeleteFile(string fileName)
    {
        ((EventHandler)delegate { FindAndDeleteFile(fileName); }).BeginInvoke(null, null, null, null);
    }

    private void FindAndDeleteFile(string fileName)
    {
        foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems)
        {
            if (projectItem.get_FileNames(0) == fileName)
            {
                projectItem.Delete();
                return;
            }
        }
    }
}
#>

MultiDocument.ttinclude

DBSchema.ttinclude主要實現了數據庫工廠的功能。注：請將數據庫連接字符串改成您自己的。

MultiDocument.ttinclude主要實現了多文檔的功能。

2.3.2、生成實體類的文本模板

<#@ template debug="true" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Text" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ output extension=".cs" #>
<#@ include file="T4Code/DBSchema.ttinclude"#>
<#@ include file="T4Code/MultiDocument.ttinclude"#>
<# var manager = new Manager(Host, GenerationEnvironment, true) { OutputPath = Path.GetDirectoryName(Host.TemplateFile)}; #>
<#
    //System.Diagnostics.Debugger.Launch();//調試
    var dbSchema = DBSchemaFactory.GetDBSchema();
    List<string> tableList = dbSchema.GetTableList();
    foreach (string tableName in tableList)
    {
        manager.StartBlock(tableName+".cs");
        DataTable table = dbSchema.GetTableMetadata(tableName);

        //獲取主鍵
        string strKey = string.Empty;
        foreach (DataRow dataRow in table.Rows)
        {
            if ((bool)dataRow["ISKEY"] == true)
            {
                strKey = dataRow["FIELD_NAME"].ToString();
                break;
            }
        }
        
#>
//-------------------------------------------------------------------------------
// 此代碼由T4模板MultiModelAuto自動生成
// 生成時間 <#= DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") #>
// 對此文件的更改可能會導致不正確的行為，並且如果重新生成代碼，這些更改將會丟失。
//-------------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Text;
using Dapper;

namespace LinkTo.Test.ConsoleDapper
{
    [Table("<#= tableName #>")]
    [Serializable]
    public class <#= tableName #>
    {
<#
        foreach (DataRow dataRow in table.Rows)
        {
            //獲取數據類型
            string dbDataType = dataRow["DATATYPE"].ToString();
            string dataType = string.Empty;
                    
            switch (dbDataType)
            {
                case "decimal":
                case "numeric":
                case "money":
                case "smallmoney":
                    dataType = "decimal?";
                    break;
                case "char":
                case "nchar":
                case "varchar":
                case "nvarchar":
                case "text":
                case "ntext":
                    dataType = "string";
                    break;
                case "uniqueidentifier":
                    dataType = "Guid?";
                    break;
                case "bit":
                    dataType = "bool?";
                    break;
                case "real":
                    dataType = "Single?";
                    break;
                case "bigint":
                    dataType = "long?";
                    break;
                case "int":
                    dataType = "int?";
                    break;
                case "tinyint":
                case "smallint":
                    dataType = "short?";
                    break;
                case "float":
                    dataType = "float?";
                    break;
                case "date":
                case "datetime":
                case "datetime2":
                case "smalldatetime":
                    dataType = "DateTime?";
                    break;
                case "datetimeoffset ":
                    dataType = "DateTimeOffset?";
                    break;
                case "timeSpan ":
                    dataType = "TimeSpan?";
                    break;
                case "image":
                case "binary":
                case "varbinary":
                    dataType = "byte[]";
                    break;
                default:
                    break;
            }
            if (dataRow["FIELD_NAME"].ToString() == strKey)
            {
#>
        [Key]
        public <#= dataType #> <#= dataRow["FIELD_NAME"].ToString() #> {get; set;}
<#
            }
            else
            {
#>

        public <#= dataType #> <#= dataRow["FIELD_NAME"].ToString() #> {get; set;}
<# 
            }
        }
#>
    }
}
<#
        manager.EndBlock();
    }
    dbSchema.Dispose();
    manager.Process(true);
#>

MultiModelAuto.tt

三、CRUD

3.1、connectionStrings

在App.config中添加數據庫連接字符串：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <startup> 
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />
  </startup>
  <connectionStrings>
    <add name="connString" connectionString="Server=.;Database=Test;Uid=sa;Pwd=********;" />
  </connectionStrings>
</configuration>

View Code

添加一個DapperHelper類，實現數據庫連接及后續的CRUD。

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Dapper;

namespace LinkTo.Test.ConsoleDapper
{
    public class DapperHelper
    {
        public IDbConnection Connection = null;
        public static string ConnectionString = ConfigurationManager.ConnectionStrings["connString"].ConnectionString;

        public DapperHelper()
        { }

        private IDbConnection GetCon()
        {
            if (Connection == null)
            {
                Connection = new SqlConnection(ConnectionString);
            }
            else if (Connection.State == ConnectionState.Closed)
            {
                Connection.ConnectionString = ConnectionString;
            }
            else if (Connection.State == ConnectionState.Broken)
            {
                Connection.Close();
                Connection.ConnectionString = ConnectionString;
            }
            return Connection;
        }
    }
}

View Code

3.2、Create

a1）通過SQL插入單條數據(帶參數)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL插入單條數據(帶參數)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? InsertWithSqlA()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "INSERT INTO Student (Name,Age,Gender) VALUES (@Name,@Age,@Gender)";
                return conn.Execute(strSql, new { Name = "Hello", Age = 18, Gender = "male" });
            }
        }

View Code

a2）通過SQL插入單條數據(帶實體)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL插入單條數據(帶實體)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? InsertWithSqlB()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "INSERT INTO Student (Name,Age,Gender) VALUES (@Name,@Age,@Gender)";
                Student student = new Student
                {
                    Name = "Hello",
                    Age = 18,
                    Gender = "male"
                };
                return conn.Execute(strSql, student);
            }
        }

View Code

a3）通過SQL插入單條數據(帶實體)，返回主鍵值。

        /// <summary>
        /// 通過SQL插入單條數據(帶實體)，返回主鍵值。
        /// </summary>
        /// <returns></returns>
        public int? InsertWithSqlC()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "INSERT INTO Student (Name,Age,Gender) VALUES (@Name,@Age,@Gender)";
                Student student = new Student
                {
                    Name = "Hello",
                    Age = 18,
                    Gender = "male"
                };
                strSql += " SELECT SCOPE_IDENTITY()";
                return conn.QueryFirstOrDefault<int>(strSql, student);
            }
        }

View Code

a4）通過SQL插入多條數據(帶實體)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL插入多條數據(帶實體)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? InsertWithSqlD()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "INSERT INTO Student (Name,Age,Gender) VALUES (@Name,@Age,@Gender)";
                List<Student> list = new List<Student>();
                for (int i = 0; i < 3; i++)
                {
                    Student student = new Student
                    {
                        Name = "World" + i.ToString(),
                        Age = 18,
                        Gender = "male"
                    };
                    list.Add(student);
                }
                return conn.Execute(strSql, list);
            }
        }

View Code

b）通過實體插入數據，返回結果是主鍵值。

        /// <summary>
        /// 通過實體插入數據，返回結果是主鍵值。
        /// </summary>
        /// <returns></returns>
        public int? InsertWithEntity()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                var entity = new Student { Name = "World", Age = 18, Gender = "male" };
                return conn.Insert(entity);
            }
        }

View Code

3.3、Read

a1）通過SQL查詢數據（查詢所有數據）

        /// <summary>
        /// 通過SQL查詢數據(查詢所有數據)
        /// </summary>
        /// <returns></returns>
        public IEnumerable<Student> GetStudentList1()
        {
            string strSql = "SELECT * FROM Student";
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Query<Student>(strSql);
            }
        }

View Code

a2）通過SQL查詢數據（帶參數）

        /// <summary>
        /// 通過SQL查詢數據(帶參數)
        /// </summary>
        /// <param name="studentID"></param>
        /// <returns></returns>
        public Student GetStudentList1A(int studentID)
        {
            string strSql = "SELECT * FROM Student WHERE StudentID=@StudentID";
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Query<Student>(strSql, new { StudentID = studentID }).FirstOrDefault();
            }
        }

View Code

a3）通過SQL查詢數據（IN）

        /// <summary>
        /// 通過SQL查詢數據(IN)
        /// </summary>
        /// <param name="studentID"></param>
        /// <returns></returns>
        public IEnumerable<Student> GetStudentList1B(string studentID)
        {
            string strSql = "SELECT * FROM Student WHERE StudentID IN @StudentID";
            var idArr = studentID.Split(',');
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Query<Student>(strSql, new { StudentID = idArr });
            }
        }

View Code

b1）通過實體查詢數據（查詢所有數據）

        /// <summary>
        /// 通過實體詢數據(查詢所有數據)
        /// </summary>
        /// <returns></returns>
        public IEnumerable<Student> GetStudentList2()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.GetList<Student>();
            }
        }

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b2）通過實體查詢數據（指定ID）

        /// <summary>
        /// 通過實體詢數據(指定ID)
        /// </summary>
        /// <param name="studentID"></param>
        /// <returns></returns>
        public Student GetStudentList2A(int studentID)
        {
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Get<Student>(studentID);
            }
        }

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b3）通過實體查詢數據（帶參數）

        /// <summary>
        /// 通過實體詢數據(帶參數)
        /// </summary>
        /// <param name="studentID"></param>
        /// <returns></returns>
        public Student GetStudentList2B(int studentID)
        {
            using (var conn = GetCon())
            {
                conn.Open();
                return conn.GetList<Student>(new { StudentID = studentID }).FirstOrDefault();
            }
        }

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c1）多表查詢(QueryMultiple)，主要操作：通過QueryMultiple方法，返回查詢中每條SQL語句的數據集合。

        /// <summary>
        /// 多表查詢(QueryMultiple)
        /// </summary>
        /// <returns></returns>
        public string GetMultiEntityA()
        {
            string strSql = "SELECT * FROM Student AS A;SELECT * FROM Teacher AS A";
            StringBuilder sbStudent = new StringBuilder();
            StringBuilder sbTeacher = new StringBuilder();
            using (var conn = GetCon())
            {
                conn.Open();
                var grid = conn.QueryMultiple(strSql);
                var students = grid.Read<Student>();
                var teachers = grid.Read<Teacher>();
                foreach (var item in students)
                {
                    sbStudent.Append($"StudentID={item.StudentID} Name={item.Name} Age={item.Age} Gender={item.Gender}\n");
                }
                foreach (var item in teachers)
                {
                    sbTeacher.Append($"TeacherID={item.TeacherID} Name={item.Name}\n");
                }
                return sbStudent.ToString() + sbTeacher.ToString();
            }
        }

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c2）多表查詢(Query)，主要操作：通過SQL進行多表關聯查詢，返回查詢結果的數據集合。

        /// <summary>
        /// 多表查詢(Query)
        /// </summary>
        /// <returns></returns>
        public string GetMultiEntityB()
        {
            string strSql = "SELECT A.Name CourseName,B.Name TeacherName FROM Course A INNER JOIN Teacher B ON A.TeacherID=B.TeacherID";
            StringBuilder sbResult = new StringBuilder();
            using (var conn = GetCon())
            {
                conn.Open();
                var query = conn.Query(strSql);
                query.AsList().ForEach(q =>
                {
                    sbResult.Append($"CourseName={q.CourseName} TeacherName={q.TeacherName}\n");
                });
                return sbResult.ToString();
            }
        }

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3.4、Update

a1）通過SQL更新數據(帶參數)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL更新數據(帶參數)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? UpdateWithSqlA()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "UPDATE Student SET Name=@Name,Age=@Age,Gender=@Gender WHERE StudentID=@StudentID";
                return conn.Execute(strSql, new { Name = "World3", Age = 19, Gender = "female", StudentID = 17 });
            }
        }

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a2）通過SQL插入單條數據(帶實體)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL更新數據(帶實體)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? UpdateWithSqlB()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "UPDATE Student SET Name=@Name,Age=@Age,Gender=@Gender WHERE StudentID=@StudentID";
                Student student = new Student
                {
                    StudentID = 17,
                    Name = "World3",
                    Age = 18,
                    Gender = "male"
                };
                return conn.Execute(strSql, student);
            }
        }

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b）通過實體更新數據，返回結果是影響行數。

        /// <summary>
        /// 通過實體更新數據，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? UpdateWithEntity()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                var entity = new Student { StudentID = 17, Name = "World4", Age = 18, Gender = "male" };
                return conn.Update(entity);
            }
        }

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3.5、Delete

a）通過SQL刪除數據(帶參數)，返回結果是影響行數。

        /// <summary>
        /// 通過SQL刪除數據(帶參數)，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? DeleteWithSql()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                string strSql = "DELETE FROM Student WHERE StudentID=@StudentID";
                return conn.Execute(strSql, new { StudentID = 16 });
            }
        }

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b）通過實體刪除數據，返回結果是影響行數。

        /// <summary>
        /// 通過實體刪除數據，返回結果是影響行數。
        /// </summary>
        /// <returns></returns>
        public int? DeleteWithEntity()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                var entity = new Student { StudentID = 17 };
                return conn.Delete(entity);
            }
        }

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四、Procedure

4.1、帶輸出參數的存儲過程

CREATE PROCEDURE [dbo].[GetStudentAge]
    @StudentID INT,
    @Name NVARCHAR(50) OUTPUT
AS
BEGIN
    DECLARE @Age SMALLINT
    SELECT @Name=Name,@Age=Age FROM Student WHERE StudentID=@StudentID
    SELECT @Age
END

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        /// <summary>
        /// 帶輸出參數的存儲過程
        /// </summary>
        /// <param name="studentID"></param>
        /// <returns></returns>
        public Tuple<string, int> GetStudentAge(int studentID)
        {
            int age = 0;
            var para = new DynamicParameters();
            para.Add("StudentID", 1);
            para.Add("Name", string.Empty, DbType.String, ParameterDirection.Output);

            using (var conn = GetCon())
            {
                conn.Open();
                age = conn.Query<int>("GetStudentAge", para, commandType: CommandType.StoredProcedure).FirstOrDefault();
            }

            return Tuple.Create(para.Get<string>("Name"), age);
        }

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五、Transaction

5.1、在IDbConnection下事務，主要操作：在執行Insert方法時傳入Transaction；在正常情況下Commit事務；在異常時回滾事務。

        /// <summary>
        /// 在IDbConnection下事務
        /// </summary>
        /// <returns></returns>
        public bool InsertWithTran()
        {
            using (var conn = GetCon())
            {
                conn.Open();
                int studentID = 0, teacherID = 0, result = 0;
                var student = new Student { Name = "Sandy", Age = 18, Gender = "female" };
                var teacher = new Teacher { Name = "Luci" };
                var tran = conn.BeginTransaction();
                try
                {
                    studentID = conn.Insert(student, tran).Value;
                    result++;
                    teacherID = conn.Insert(teacher, tran).Value;
                    result++;
                    tran.Commit();
                }
                catch
                {
                    result = 0;
                    tran.Rollback();
                }
                return result > 0;
            }
        }

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5.2、在存儲過程下事務，主要操作：在存儲過程中進行事務；通過DynamicParameters傳遞參數給存儲過程；通過Query調用存儲過程。

CREATE PROCEDURE [dbo].[InsertData]
    --Student
    @StudentName NVARCHAR(50),
    @Age SMALLINT,
    @Gender NVARCHAR(10),
    --Teacher
    @TeacherName NVARCHAR(50)
AS
BEGIN
    --變量定義
    DECLARE @Result BIT=1    --結果標識
    
    --事務開始
    BEGIN TRANSACTION

    --數據插入
    INSERT INTO Student (Name,Age,Gender) VALUES (@StudentName,@Age,@Gender)
    INSERT INTO Teacher (Name) VALUES (@TeacherName)
    
    --事務執行
    IF @@ERROR=0
    BEGIN
        COMMIT TRANSACTION
    END
    ELSE
    BEGIN
        SET @Result=0
        ROLLBACK TRANSACTION
    END

    --結果返回
    SELECT @Result
END

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        /// <summary>
        /// 在存儲過程下事務
        /// </summary>
        /// <returns></returns>
        public bool InsertWithProcTran()
        {
            var para = new DynamicParameters();
            para.Add("StudentName", "Hanmeimei");
            para.Add("Age", 18);
            para.Add("Gender", "female");
            para.Add("TeacherName", "Angel");

            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Query<bool>("InsertData", para, commandType: CommandType.StoredProcedure).FirstOrDefault();
            }
        }

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六、Paging

6.1、簡單分頁

        /// <summary>
        /// 簡單分頁
        /// </summary>
        /// <param name="beginRowNum"></param>
        /// <param name="endRowNum"></param>
        /// <returns></returns>
        public IEnumerable<Student> GetPaging(int beginRowNum = 1, int endRowNum = 5)
        {
            string strSql =
                    "SELECT * FROM " +
                        "( " +
                            "SELECT A.*, ROW_NUMBER() OVER(ORDER BY A.StudentID) RowNum " +
                            "FROM Student AS A " +
                        ") B " +
                    "WHERE B.RowNum BETWEEN @BeginRowNum AND @EndRowNum " +
                    "ORDER BY B.RowNum ";

            using (var conn = GetCon())
            {
                return conn.Query<Student>(strSql, new { BeginRowNum = beginRowNum, EndRowNum = endRowNum });
            }
        }

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6.2、通用分頁

CREATE PROCEDURE [dbo].[PageList]
     @TableName VARCHAR(200),       --表名
     @FieldName VARCHAR(500) = '*', --字段名
     @Where VARCHAR(100) = NULL,    --條件語句
     @GroupBy VARCHAR(100) = NULL,  --分組字段
     @OrderBy VARCHAR(100),         --排序字段
     @PageIndex INT = 1,            --當前頁數
     @PageSize INT = 20,            --每頁顯示記錄數
     @TotalCount INT = 0 OUTPUT     --總記錄數
AS
BEGIN
    --SQL拼接語句
    DECLARE @SQL NVARCHAR(4000)

    --總記錄數
    SET @SQL='SELECT @RecordCount=COUNT(1) FROM ' + @TableName
    IF (ISNULL(@Where,'')<>'')
        SET @SQL=@SQL+' WHERE '+@Where
    ELSE IF (ISNULL(@GroupBy,'')<>'')
        SET @SQL=@SQL+' GROUP BY '+@GroupBy

    EXEC SP_EXECUTESQL @SQL,N'@RecordCount INT OUTPUT',@TotalCount OUTPUT

    --總頁數
    DECLARE @PageCount INT
    SELECT @PageCount=CEILING((@TotalCount+0.0)/@PageSize)
    
    --簡單分頁
    SET @SQL='SELECT * FROM (SELECT ROW_NUMBER() OVER (ORDER BY '+@OrderBy+') AS RowNum,' + @FieldName + ' FROM '+@TableName+' AS A'
    IF (ISNULL(@Where,'')<>'')
        SET @SQL=@SQL+' WHERE '+@Where
    ELSE IF (ISNULL(@GroupBy,'')<>'')
        SET @SQL=@SQL+' GROUP BY '+@GroupBy

    IF (@PageIndex<=0)
        SET @PageIndex=1
    IF @PageIndex>@PageCount
        SET @PageIndex=@PageCount
     
    DECLARE @BeginRowNum INT,@EndRowNum INT  
    SET @BeginRowNum=(@PageIndex-1)*@PageSize+1
    SET @EndRowNum=@BeginRowNum+@PageSize-1

    SET @SQL=@SQL + ') AS B WHERE B.RowNum BETWEEN '+CONVERT(VARCHAR(32),@BeginRowNum)+' AND '+CONVERT(VARCHAR(32),@EndRowNum)
    EXEC(@SQL)
END

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        /// <summary>
        /// 通用分頁
        /// </summary>
        /// <returns></returns>
        public IEnumerable<T> GetCommonPaging<T>(string tableName, string fieldName, string where, string groupby, string orderby, int pageIndex, int pageSize)
        {
            var para = new DynamicParameters();
            para.Add("TableName", tableName);
            para.Add("FieldName", fieldName);
            para.Add("Where", where);
            para.Add("GroupBy", groupby);
            para.Add("OrderBy", orderby);
            para.Add("PageIndex", pageIndex);
            para.Add("PageSize", pageSize);
            para.Add("TotalCount", dbType: DbType.Int32, direction: ParameterDirection.Output);

            using (var conn = GetCon())
            {
                conn.Open();
                return conn.Query<T>("PageList", para, commandType: CommandType.StoredProcedure);
            }
        }

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