### Query Data Example

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

A C# example demonstrating how to query a collection of Blog entities with filtering, ordering, skipping, and limiting.

```csharp
var blogs = fsql.Select<Blog>()
    .Where(b => b.Rating > 3)
    .OrderBy(b => b.Url)
    .Skip(100)
    .Limit(10) //Query the record from line 100 to line 110
    .ToList();
```

--------------------------------

### Insert Data Example

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

A C# example showing how to insert a new Blog entity into the database and retrieve its auto-generated identity value.

```csharp
var blog = new Blog { Url = "http://sample.com" };
blog.BlogId = (int)fsql.Insert<Blog>()
    .AppendData(blog)
    .ExecuteIdentity();
```

--------------------------------

### Update Data Example

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

A C# example demonstrating how to update existing Blog entities in the database based on a condition and return the number of affected rows.

```csharp
fsql.Update<Blog>()
    .Set(b => b.Url, "http://sample2222.com")
    .Where(b => b.Url == "http://sample.com")
    .ExecuteAffrows();
```

--------------------------------

### Delete Data Example

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

A C# example showing how to delete Blog entities from the database based on a condition and return the number of affected rows.

```csharp
fsql.Delete<Blog>()
    .Where(b => b.Url == "http://sample.com")
    .ExecuteAffrows();
```

--------------------------------

### Install FreeSql Packages

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

Commands to add FreeSql and a specific provider (Sqlite) to a .NET project using the dotnet CLI or Package Manager Console.

```bash
dotnet add packages FreeSql
dotnet add packages FreeSql.Provider.Sqlite
```

```powershell
Install-Package FreeSql
Install-Package FreeSql.Provider.Sqlite
```

--------------------------------

### Quick Start

Source: https://github.com/dotnetcore/freesql/blob/master/README.md

Example of setting up FreeSql with SQLite and defining entities.

```csharp
static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
  .UseConnectionString(FreeSql.DataType.Sqlite, @"Data Source=document.db")
  .UseAutoSyncStructure(true) //automatically synchronize the entity structure to the database
  .Build(); //be sure to define as singleton mode

class Song {
  [Column(IsIdentity = true)]
  public int Id { get; set; }
  public string Title { get; set; }
  public string Url { get; set; }
  public DateTime CreateTime { get; set; }
  
  public ICollection<Tag> Tags { get; set; }
}
class Song_tag {
  public int Song_id { get; set; }
  public Song Song { get; set; }
  
  public int Tag_id { get; set; }
  public Tag Tag { get; set; }
}
class Tag {
  [Column(IsIdentity = true)]
  public int Id { get; set; }
  public string Name { get; set; }
  
  public int? Parent_id { get; set; }
  public Tag Parent { get; set; }
  
  public ICollection<Song> Songs { get; set; }
  public ICollection<Tag> Tags { get; set; }
}
```

--------------------------------

### Install FreeSql.Repository

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Install the FreeSql.Repository package using the .NET CLI.

```bash
dotnet add package FreeSql.Repository
```

--------------------------------

### Install Packages

Source: https://github.com/dotnetcore/freesql/blob/master/Extensions/FreeSql.Extensions.BaseEntity/README.MD

Install the necessary packages for FreeSql.Extensions.BaseEntity and a database provider.

```bash
dotnet add package FreeSql.Extensions.BaseEntity
dotnet add package FreeSql.Provider.Sqlite
```

--------------------------------

### Sharding Example (Table Splitting)

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Example of creating a sharded repository for logs, splitting by year and month.

```csharp
var logRepository = fsql.GetGuidRepository<Log>(null, oldname => $"{oldname}_{DateTime.Now.ToString("YYYYMM")}");
```

--------------------------------

### Installation

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.DbContext/readme.md

Install the FreeSql.DbContext package using the dotnet add package command.

```bash
dotnet add package FreeSql.DbContext
```

--------------------------------

### WithSql Example

Source: https://github.com/dotnetcore/freesql/wiki/Return-Data

Illustrates how to use `WithSql` to execute a raw SQL query as a subquery, with an example of pagination.

```csharp
fsql.Select<Topic>()
  .WithSql("select * from Topic where clicks > @val", new { val = 10 })
  .Page(1, 10)
  .ToList()

//SELECT a.`Id`, a.`Clicks`, a.`CategoryId`, a.`Title`, a.`CreateTime` 
//FROM (select * from Topic where clicks > @val) a 
```

--------------------------------

### Install FreeSql.Extensions.Linq

Source: https://github.com/dotnetcore/freesql/wiki/Linq-to-Sql

Command to install the FreeSql.Extensions.Linq package for FreeSql v1.4.0+.

```bash
dotnet add package FreeSql.Extensions.Linq
```

--------------------------------

### .NET Core Singleton IFreeSql Declaration

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

Example of how to register IFreeSql as a singleton service in .NET Core's Startup.cs, configuring it with a connection string and enabling automatic structure synchronization.

```csharp
services.AddSingleton<IFreeSql>(r =>
{
    IFreeSql fsql = new FreeSql.FreeSqlBuilder()
        .UseConnectionString(FreeSql.DataType.Sqlite, @"Data Source=db1.db")
        //Automatically synchronize the entity structure to the database.
        //FreeSql will not scan the assembly, and will generate a table if and only when the CRUD instruction is executed.
        .UseAutoSyncStructure(true)
        .Build();
    return fsql;
});
```

--------------------------------

### UnitOfWork Dependency Injection Setup

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Setup for injecting UnitOfWork and UnitOfWorkRepository into the service collection.

```csharp
//第一步：
public class UnitOfWorkRepository<TEntity, TKey> : BaseRepository<TEntity, TKey>
{
  public UnitOfWorkRepository(IFreeSql fsql, IUnitOfWork uow) : base(fsql, null, null)
  {
    this.UnitOfWork = uow;
  }
}
public class UnitOfWorkRepository<TEntity> : BaseRepository<TEntity, int>
{
  public UnitOfWorkRepository(IFreeSql fsql, IUnitOfWork uow) : base(fsql, null, null)
  {
    this.UnitOfWork = uow;
  }
}

//第二步：
public void ConfigureServices(IServiceCollection services)
{
  services.AddSingleton<IFreeSql>(fsql);
  services.AddScoped<FreeSql.IUnitOfWork>(sp => fsql.CreateUnitOfWork());

  services.AddScoped(typeof(IReadOnlyRepository<>), typeof(UnitOfWorkRepository<>));
  services.AddScoped(typeof(IBasicRepository<>), typeof(UnitOfWorkRepository<>));
  services.AddScoped(typeof(BaseRepository<>), typeof(UnitOfWorkRepository<>));

  services.AddScoped(typeof(IReadOnlyRepository<,>), typeof(UnitOfWorkRepository<,>));
  services.AddScoped(typeof(IBasicRepository<,>), typeof(UnitOfWorkRepository<,>));
  services.AddScoped(typeof(BaseRepository<,>), typeof(UnitOfWorkRepository<,>));

  //批量注入程序集内的所有自建仓储类，可以根据自己需要来修改
  Assembly[] assemblies = new [] { typeof(XxxRepository).Assembly };
  if (assemblies?.Any() == true)
      foreach (var asse in assemblies)
        foreach (var repo in asse.GetTypes().Where(a => a.IsAbstract == false && typeof(UnitOfWorkRepository).IsAssignableFrom(a)))
          services.AddScoped(repo);
}
```

--------------------------------

### Join Example

Source: https://github.com/dotnetcore/freesql/wiki/Linq-to-Sql

Examples of performing inner joins between tables.

```csharp
var t1 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId
    select a
).ToList();

var t2 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId
    select new { a.id, bid = b.id }
).ToList();

var t3 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId
    where a.id == item.id
    select new { a.id, bid = b.id }
).ToList();
```

--------------------------------

### Install FreeSql.Generator

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

Installs the FreeSql.Generator tool globally using the .NET Core CLI.

```dotnetcli
dotnet tool install -g FreeSql.Generator
```

--------------------------------

### FreeSql.Generator Example

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

Example command for FreeSql.Generator using various options including the -DB parameter.

```bash
FreeSql.Generator -Razor 1 -NameOptions 0,0,0,1 -NameSpace LinCms.Core.Entities -DB "MySql,Data Source=127.0.0.1;Port=3306;User ID=root;Password=123456;Initial Catalog=lincms;Charset=utf8;SslMode=none;Max pool size=2"
```

--------------------------------

### Accessing MySQL Database Example

Source: https://github.com/dotnetcore/freesql/blob/master/Providers/FreeSql.Provider.Custom/readme.md

Example demonstrating how to configure FreeSql to access a MySQL database using the Custom provider.

```csharp
var fsql = new FreeSqlBuilder()
    .UseConnectionFactory(DataType.CustomMySql, () => 
        new MySqlConnection("Data Source=..."))
    .UseNoneCommandParameter(true)
    .UseMonitorCommand(cmd => Console.WriteLine(cmd.CommandText))
    .Build();
fsql.SetDbProviderFactory(MySqlConnectorFactory.Instance);
```

--------------------------------

### Install FreeSql Provider for SQL Server

Source: https://github.com/dotnetcore/freesql/wiki/Dapper比较

Command to install the FreeSql SQL Server provider package.

```bash
dotnet add packages FreeSql.Provider.SqlServer
```

```powershell
Install-Package FreeSql.Provider.SqlServer
```

--------------------------------

### CaseWhen Example

Source: https://github.com/dotnetcore/freesql/wiki/Linq-to-Sql

Example demonstrating the use of 'CaseWhen' logic within a select statement.

```csharp
var t1 = (
    from a in fsql.Select<Student>()
    where a.id == item.id
    select new {
        a.id,
        a.name,
        testsub = new {
            time = a.age > 10 ? "大于" : "小于或等于"
        }
    }
).ToList();
```

--------------------------------

### FreeSql.Generator Command Example

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

An example command demonstrating how to use FreeSql.Generator to generate entity classes with specific options.

```bash
FreeSql.Generator -Razor 1 -NameOptions 0,0,0,0 -NameSpace MyProject -DB "MySql,Data Source=127.0.0.1;..."
```

--------------------------------

### Install FreeSql Packages

Source: https://github.com/dotnetcore/freesql/wiki/Install

Command to add the FreeSql core package, the DbContext package, and the MySqlConnector provider package using the .NET CLI.

```bash
dotnet add package FreeSql
dotnet add package FreeSql.DbContext
dotnet add package FreeSql.Provider.MySqlConnector
```

--------------------------------

### Custom Adapter Example for MSSQL2000

Source: https://github.com/dotnetcore/freesql/blob/master/Providers/FreeSql.Provider.Custom/readme.md

Example of creating a custom adapter for MSSQL2000 by inheriting from FreeSql.Custom.CustomAdapter.

```csharp
class Mssql2000Adapter : FreeSql.Custom.CustomAdapter
{
    public override string InsertAfterGetIdentitySql => "SELECT SCOPE_IDENTITY()";
    //可以重写更多的设置
}

static IFreeSql fsql = new FreeSqlBuilder()
    .UseConnectionString(DataType.Custom, () => new SqlConnection(@"Data Source=..."))
    .Build(); //be sure to define as singleton mode

fsql.SetCustomAdapter(new Mssql2000Adapter());
```

--------------------------------

### Install FreeSql.DbContext for .NET Framework

Source: https://github.com/dotnetcore/freesql/wiki/Repository

Command to install the FreeSql.DbContext package for .NET Framework environments.

```bash
Install-Package FreeSql.DbContext
```

--------------------------------

### Repository Example

Source: https://github.com/dotnetcore/freesql/blob/master/README.md

Example of using the repository pattern with FreeSql, including transactional operations.

```csharp
[Transactional]
public void Add() {
  var repo = ioc.GetService<BaseRepository<Tag>>();
  repo.DbContextOptions.EnableCascadeSave = true;

  var item = new Tag {
    Name = "testaddsublist",
    Tags = new[] {
      new Tag { Name = "sub1" },
      new Tag { Name = "sub2" }
    }
  };
  repo.Insert(item);
}
```

--------------------------------

### Example of using Ioc + Login Information for Auditing

Source: https://github.com/dotnetcore/freesql/wiki/Repository

Example demonstrating how to use dependency injection and login information to automatically populate audit fields during insert/update operations.

```csharp
services.AddSingleton(fsql);
services.AddScoped(r => new MyRepositoryOptions
{
    AuditValue = e => {
        var user = r.GetService<User>();
        if (user == null) return;
        if (e.AuditValueType == AuditValueType.Insert &&
            e.Object is IEntityCreated obj1 && obj1 != null) {
            obj1.CreatedUserId = user.Id;
            obj1.CreatedUserName = user.Username;
        }
        if (e.AuditValueType == AuditValueType.Update &&
            e.Object is IEntityModified obj2 && obj2 != null) {
            obj2.ModifiedUserId = user.Id;
            obj2.ModifiedUserName = user.Username;
        }
    }
});
services.AddScoped(typeof(IBaseRepository<>), typeof(MyRepository<>));
services.AddScoped(typeof(IBaseRepository<,>), typeof(MyRepository<,>));

//以下实现 MyRepository
class MyRepository<TEntity, TKey> : BaseRepository<TEntity, TKey> where TEntity : class
{
    public MyRepository(IFreeSql fsql, MyRepositoryOptions options) : base(fsql, null, null)
    {
        if (options?.AuditValue != null) DbContextOptions.AuditValue += (_, e) => options.AuditValue(e);
    }
}
class MyRepository<TEntity> : MyRepository<TEntity, long> where TEntity : class
{
    public MyRepository(IFreeSql fsql, MyRepositoryOptions options) : base(fsql, options) { }
}
class MyRepositoryOptions
{
    public Action<DbContextAuditValueEventArgs> AuditValue { get; set; }
}
```

--------------------------------

### Get Repository using extension method

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Get a repository instance for the Song entity using the extension method on IFreeSql.

```csharp
var curd = fsql.GetRepository<Song>();
```

--------------------------------

### LeftJoin Example

Source: https://github.com/dotnetcore/freesql/wiki/Linq-to-Sql

Examples of performing left joins (including DefaultIfEmpty) between tables.

```csharp
var t1 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId into temp
    from tc in temp.DefaultIfEmpty()
    select a
).ToList();

var t2 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId into temp
    from tc in temp.DefaultIfEmpty()
    select new { a.id, bid = tc.id }
).ToList();

var t3 = (
    from a in fsql.Select<Student>()
    join b in fsql.Select<School>() on a.id equals b.StudentId into temp
    from tc in temp.DefaultIfEmpty()
    where a.id == item.id
    select new { a.id, bid = tc.id }
).ToList();
```

--------------------------------

### DbContext Usage Example

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.DbContext/readme.md

Example demonstrating adding, updating, and removing entities using DbContext, followed by SaveChangesAsync.

```csharp
long id = 0;

using (var ctx = new SongContext()) {

    var song = new Song { };
    await ctx.Songs.AddAsync(song);
    id = song.Id;

    var adds = Enumerable.Range(0, 100)
        .Select(a => new Song { Create_time = DateTime.Now, Is_deleted = false, Title = "xxxx" + a, Url = "url222" })
        .ToList();
    await ctx.Songs.AddRangeAsync(adds);

    for (var a = 0; a < adds.Count; a++)
        adds[a].Title = "dkdkdkdk" + a;

    ctx.Songs.UpdateRange(adds);

    ctx.Songs.RemoveRange(adds.Skip(10).Take(20).ToList());

    //ctx.Songs.Update(adds.First());

    adds.Last().Url = "skldfjlksdjglkjjcccc";
    ctx.Songs.Update(adds.Last());

    //throw new Exception("回滚");

    await ctx.SaveChangesAsync();
}
```

--------------------------------

### Blog Entity Model

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

An example of a C# entity class representing a database table, with FreeSql specific annotations for identity and primary key.

```csharp
using FreeSql.DataAnnotations;
using System;

public class Blog {
    [Column(IsIdentity = true, IsPrimary = true)]
    public int BlogId { get; set; }
    public string Url { get; set; }
    public int Rating { get; set; }
}
```

--------------------------------

### .NET Framework Singleton IFreeSql Declaration

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

Example of declaring a static singleton instance of IFreeSql for use in .NET Framework applications, using Lazy<T> for thread-safe initialization.

```csharp
public class DB
{
    static Lazy<IFreeSql> sqliteLazy = new Lazy<IFreeSql>(() => {
        var fsql = new FreeSql.FreeSqlBuilder()
            .UseConnectionString(FreeSql.DataType.Sqlite, @"Data Source=db1.db")
            .UseAutoSyncStructure(true)
            .Build();
        return fsql;
    });
    public static IFreeSql Sqlite => sqliteLazy.Value;
}
```

--------------------------------

### Basic Repository Initialization

Source: https://github.com/dotnetcore/freesql/wiki/Repository-Layer

Initializes User and Topic repositories.

```csharp
var userRepository = fsql.GetRepository<User>();
var topicRepository = fsql.GetRepository<Topic>();
```

--------------------------------

### User with Guid primary key

Source: https://github.com/dotnetcore/freesql/wiki/BaseEntity

Example of defining a User entity with a Guid primary key, which will automatically generate an ordered, unique Guid value upon saving.

```csharp
public class User : BaseEntity<UserGroup, Guid> {
    public string UserName { get; set; }
}
```

--------------------------------

### Getting DbContext in MVC

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.DbContext/readme.md

Example of injecting DbContext into an MVC controller.

```csharp
IFreeSql _orm;
public ValuesController(SongContext songContext) {
}
```

--------------------------------

### Dependency Injection Setup

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Configure dependency injection for IFreeSql and FreeSql.Repository, including global filters.

```csharp
public void ConfigureServices(IServiceCollection services) {
    
    services.AddSingleton<IFreeSql>(Fsql);
    services.AddFreeRepository(filter => filter
        .Apply<ISoftDelete>("SoftDelete", a => a.IsDeleted == false)
        .Apply<ITenant>("Tenant", a => a.TenantId == 1)
        ,
        this.GetType().Assembly
    );
}

//在控制器使用
public SongsController(GuidRepository<Song> repos1) {
}
```

--------------------------------

### Install and Use JsonMap Extension

Source: https://github.com/dotnetcore/freesql/blob/master/Extensions/FreeSql.Extensions.JsonMap/README.MD

Instructions for installing the FreeSql.Extensions.JsonMap package and enabling the JsonMap functionality. Includes an example of mapping a complex object to a string column using the JsonMap attribute.

```csharp
fsql.UseJsonMap(); //Turn on function

class TestConfig
{
    public int clicks { get; set; }
    public string title { get; set; }
}

[Table(Name = "sysconfig")]
public class S_SysConfig<T>
{
    [Column(IsPrimary = true)]
    public string Name { get; set; }

    [JsonMap]
    public T Config { get; set; }
}
```

--------------------------------

### JsonMap Usage

Source: https://github.com/dotnetcore/freesql/wiki/类型映射

Example of using FreeSql's JsonMap feature to map C# objects to JSON columns in the database. Includes installation command, attribute usage, and query example.

```csharp
fsql.UseJsonMap(); //开启功能

class Table
{
    public int Id { get; set; }

    [JsonMap]
    public TableOptions Options { get; set; }
}
class TableOptions
{
    public int Value1 { get; set; }
    public string Value2 { get; set; }
}

fsql.Select<Table>().Where(a => a.Options.Value1 == 100 && a.Options.Value2 == "xx").ToList();
//WHERE json_extract(a."Options",'$.Value1') = 100 AND json_extract(a."Options",'$.Value2') = 'xx'
```

--------------------------------

### BenchmarkDotNet Configuration

Source: https://github.com/dotnetcore/freesql/wiki/Dapper比较

Configuration details for the BenchmarkDotNet performance tests.

```shell
BenchmarkDotNet=v0.12.1, OS=Windows 10.0.19044
Intel Core i7-8700K CPU 3.70GHz (Coffee Lake), 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=6.0.100
  [Host]     : .NET Core 5.0.11 (CoreCLR 5.0.1121.47308, CoreFX 5.0.1121.47308), X64 RyuJIT DEBUG
  Job-LEQVAV : .NET Core 5.0.11 (CoreCLR 5.0.1121.47308, CoreFX 5.0.1121.47308), X64 RyuJIT DEBUG

BuildConfiguration=Debug  InvocationCount=1  UnrollFactor=1
```

--------------------------------

### Distinct count of a field

Source: https://github.com/dotnetcore/freesql/wiki/Group-Aggregation-Query

Example of how to get the distinct count of a specific field using the Aggregate method.

```csharp
var list = fsql.Select<Topic>()
    .Aggregate(a => Convert.ToInt32("count(distinct title)"), out var count)
    .ToList();
```

--------------------------------

### Aggregate without Grouping

Source: https://github.com/dotnetcore/freesql/wiki/Group-Aggregation-Query

Example of using ToAggregate to get aggregate values without explicit grouping.

```csharp
var list = fsql.Select<Topic>()
    .ToAggregate(a => new 
    {
        cou1 = a.Count(), 
        arg1 = a.Avg(a.Key.Clicks), 
        arg2 = a.Sum(a.Key.Clicks > 100 ? 1 : 0)
    });
```

--------------------------------

### Distinct count using SqlExt.DistinctCount

Source: https://github.com/dotnetcore/freesql/wiki/Group-Aggregation-Query

Example of how to get the distinct count of a specific field using the SqlExt.DistinctCount extension method.

```csharp
fsql.Select<Topic>()
    .Aggregate(a => SqlExt.DistinctCount(a.Key.Title), out var count);
```

```sql
SELECT count(distinct a."title") as1 FROM "Topic" a
```

--------------------------------

### Oracle Stored Procedure to get DataTable

Source: https://github.com/dotnetcore/freesql/wiki/ADO

Example of executing an Oracle stored procedure that returns a RefCursor and retrieving it as a DataTable.

```csharp
OracleParameter p2 = null;
var dt = fsql.Ado.CommandFluent("getTableInfo")
     .CommandType(CommandType.StoredProcedure)
     .CommandTimeout(60)
     .WithParameter("out_var", null, p =>
     {
         p2 = p as OracleParameter;
         p2.OracleDbType = OracleDbType.RefCursor;
         p2.Direction = ParameterDirection.Output;
     })
     .ExecuteDataTable();
Console.WriteLine(dt.Rows.Count);
```

--------------------------------

### IOC + Login: Dependency Injection Setup

Source: https://github.com/dotnetcore/freesql/wiki/Repository-Layer

Example of integrating IOC with login information for automatic audit value population during insert/update operations.

```csharp
services.AddSingleton(fsql);
services.AddScoped(r => new MyRepositoryOptions
{
    AuditValue = e => {
        var user = r.GetService<User>();
        if (user == null) return;
        if (e.AuditValueType == AuditValueType.Insert &&
            e.Object is IEntityCreated obj1 && obj1 != null) {
            obj1.CreatedUserId = user.Id;
            obj1.CreatedUserName = user.Username;
        }
        if (e.AuditValueType == AuditValueType.Update &&
            e.Object is IEntityModified obj2 && obj2 != null) {
            obj2.ModifiedUserId = user.Id;
            obj2.ModifiedUserName = user.Username;
        }
    }
});
services.AddScoped(typeof(IBaseRepository<>), typeof(MyRepository<>));
services.AddScoped(typeof(IBaseRepository<,>), typeof(MyRepository<,>));

class MyRepository<TEntity, TKey> : BaseRepository<TEntity, TKey> where TEntity : class
{
    public MyRepository(IFreeSql fsql, MyRepositoryOptions options) : base(fsql, null, null)
    {
        if (options?.AuditValue != null) DbContextOptions.AuditValue += (_, e) => options.AuditValue(e);
    }
}
class MyRepository<TEntity> : MyRepository<TEntity, long> where TEntity : class
{
    public MyRepository(IFreeSql fsql, MyRepositoryOptions options) : base(fsql, options) { }
}
class MyRepositoryOptions
{
    public Action<DbContextAuditValueEventArgs> AuditValue { get; set; }
}
```

--------------------------------

### Basic IFreeSql Operations

Source: https://github.com/dotnetcore/freesql/wiki/Getting-Started

Illustrates the primary methods available on the IFreeSql interface for common ORM operations like Query, Insert, Update, Delete, and Transaction.

```csharp
fsql.Select<T>(); //Query
fsql.Insert<T>(); //Insert
fsql.Update<T>(); //Update
fsql.Delete<T>(); //Delete
fsql.InsertOrUpdate<T>()// Insert or Update
fsql.Transaction(..); //Transaction

fsql.CodeFirst; //CodeFirst Object
fsql.DbFirst; //DbFirst Object
fsql.Ado; //Ado Object
fsql.Aop; //Aop Object
fsql.GlobalFilter; //Gloabl Filter Object
```

--------------------------------

### Get Entity Types by Namespace

Source: https://github.com/dotnetcore/freesql/wiki/CodeFirst

A method to retrieve entity types from a specific assembly based on their namespace, filtering for classes that start with specified namespace prefixes.

```csharp
public static Type[] GetTypesByNameSpace()
{
    List<Type> tableAssembies = new List<Type>();
    List<string> entitiesFullName = new List<string>()
    {
        "LinCms.Entities.Settings",
        "LinCms.Entities.Base",
    };
    foreach (Type type in Assembly.GetAssembly(typeof(IEntity)).GetExportedTypes())
        foreach (var fullname in entitiesFullName)
            if (type.FullName.StartsWith(fullname) && type.IsClass)
                tableAssembies.Add(type);

    return tableAssembies.ToArray();
}
//或通过调用同步所有表结构
fsql.CodeFirst.SyncStructure(GetTypesByNameSpace());
```

--------------------------------

### FreeSql Initialization

Source: https://github.com/dotnetcore/freesql/wiki/Unit-of-Work

Example of initializing FreeSql with connection string and enabling automatic structure synchronization. It's recommended to define it as a singleton.

```csharp
static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connectionString)
    //Automatically synchronize the entity structure to the database.
    .UseAutoSyncStructure(true) 
    //Be sure to define as singleton mode
    .Build(); 
```

--------------------------------

### Initialization

Source: https://github.com/dotnetcore/freesql/blob/master/Extensions/FreeSql.Extensions.BaseEntity/README.MD

Initialize BaseEntity with the FreeSql instance.

```csharp
BaseEntity.Initialization(fsql, null);
```

--------------------------------

### Display FreeSql.Generator Help

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

Displays the help information for the FreeSql.Generator command-line tool.

```dotnetcli
FreeSql.Generator --help
```

--------------------------------

### Where Clause Example

Source: https://github.com/dotnetcore/freesql/wiki/Linq-to-Sql

Example of using a 'where' clause in a Linq query.

```csharp
var t1 = (
    from a in fsql.Select<Student>()
    where a.id == item.id
    select a
).ToList();
```

--------------------------------

### Get AggregateRootRepository

Source: https://github.com/dotnetcore/freesql/wiki/聚合根（实验室）

Get an instance of AggregateRootRepository for a specific entity.

```csharp
var repository = fsql.GetAggregateRootRepository<Order>();
```

--------------------------------

### Query Examples

Source: https://github.com/dotnetcore/freesql/blob/master/README.md

Demonstrates various querying capabilities including OneToOne, ManyToOne, OneToMany, ManyToMany, and conditional queries.

```csharp
//OneToOne、ManyToOne
fsql.Select<Tag>().Where(a => a.Parent.Parent.Name == "English").ToList();

//OneToMany
fsql.Select<Tag>().IncludeMany(a => a.Tags, then => then.Where(sub => sub.Name == "foo")).ToList();

//ManyToMany
fsql.Select<Song>()
  .IncludeMany(a => a.Tags, then => then.Where(sub => sub.Name == "foo"))
  .Where(s => s.Tags.Any(t => t.Name == "Chinese"))
  .ToList();

//Other
fsql.Select<YourType>()
  .Where(a => a.IsDelete == 0)
  .WhereIf(keyword != null, a => a.UserName.Contains(keyword))
  .WhereIf(role_id > 0, a => a.RoleId == role_id)
  .Where(a => a.Nodes.Any(t => t.Parent.Id == t.UserId))
  .Count(out var total)
  .Page(page, size)
  .OrderByDescending(a => a.Id)
  .ToList()
```

```csharp
fsql.Select<Song>().Where(a => new[] { 1, 2, 3 }.Contains(a.Id)).ToList();

fsql.Select<Song>().Where(a => a.CreateTime.Date == DateTime.Today).ToList();

fsql.Select<Song>().OrderBy(a => Guid.NewGuid()).Limit(10).ToList();

fsql.Select<Song>().ToList(a => new
{
    a.Id,
    Tags = fsql.Select<Tag>().ToList(),
    SongTags = fsql.Select<SongTag>().Where(b => b.TopicId == a.Id).ToList()
});
```

--------------------------------

### FreeSql Initialization and Topic Class Definition

Source: https://github.com/dotnetcore/freesql/wiki/分页查询

Initializes FreeSql as a singleton and defines the Topic entity class.

```csharp
static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connectionString)
    .Build(); //请务必定义成 Singleton 单例模式

class Topic {
    [Column(IsIdentity = true)]
    public int Id { get; set; }
    public string Title { get; set; }
    public int Clicks { get; set; }
    public DateTime CreateTime { get; set; }

    public int CategoryId {
        get;
        set;
    }
}
```

--------------------------------

### Initialize FreeSql

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

Initializes FreeSql as a Singleton instance, essential for its proper functioning.

```csharp
static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connectionString)
    .Build(); //请务必定义成 Singleton 单例模式
```

--------------------------------

### Filtering and Validation Example

Source: https://github.com/dotnetcore/freesql/blob/master/FreeSql.Repository/readme.md

Example of using filter expressions to secure data and validate input.

```csharp
var userRepository = fsql.GetGuidRepository<User>();
var topicRepository = fsql.GetGuidRepository<Topic>();

var userRepository = fsql.GetGuidRepository<User>(a => a.Id == 1);
var topicRepository = fsql.GetGuidRepository<Topic>(a => a.UserId == 1);
```

--------------------------------

### Using WithSql for Raw SQL Queries

Source: https://github.com/dotnetcore/freesql/wiki/返回数据

Demonstrates how to execute a raw SQL query with parameters using WithSql.

```csharp
fsql.Select<Topic>()
    .WithSql("select * from Topic where clicks > @val", new { val = 10 })
    .Page(1, 10)
    .ToList()
//SELECT a.`Id`, a.`Clicks`, a.`CategoryId`, a.`Title`, a.`CreateTime` 
//FROM (select * from Topic where clicks > @val) a 
```

--------------------------------

### Basic Read/Write Separation Configuration

Source: https://github.com/dotnetcore/freesql/wiki/读写分离

Demonstrates how to configure FreeSql with a master database and multiple slave databases using `UseSlave`. It also shows how to explicitly read from the master database.

```csharp
static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
    .UseConnectionString(FreeSql.DataType.MySql, connectionString)
    .UseSlave("connectionString1", "connectionString2") //使用从数据库，支持多个
    //.UseSlaveWeight(10, 5) //读权重 v3.2.100
    .Build(); //请务必定义成 Singleton 单例模式

fsql.Select<T>().Where(a => a.Id == 1).ToOne(); //读【从库】（默认）

fsql.Select<T>().Master().WhereId(a => a.Id == 1).ToOne(); //强制读【主库】

fsql.Ado.Query<T>("/*master*/ select * from t where ..."); //强制读【主库】
```

--------------------------------

### Define Entity with Guid Primary Key

Source: https://github.com/dotnetcore/freesql/blob/master/Extensions/FreeSql.Extensions.BaseEntity/README.MD

Define a User entity with a Guid primary key, which will be automatically generated.

```csharp
public class User : BaseEntity<UserGroup, Guid>
{
    public string UserName { get; set; }
}
```

--------------------------------

### DB Parameter Reference

Source: https://github.com/dotnetcore/freesql/wiki/DbFirst

Example of the -DB parameter with a MySql connection string.

```bash
-DB "MySql,Data Source=127.0.0.1;Port=3306;User ID=root;Password=123456;Initial Catalog=lincms;Charset=utf8;SslMode=none;Max pool size=2"
```

--------------------------------

### MaxLength Attribute Example

Source: https://github.com/dotnetcore/freesql/wiki/更新日志

Example demonstrating the MaxLength attribute for setting string length in entities.

```csharp
class Topic {
    [MaxLength(128)]
    public string Title { get; set; }
}
```