SqlSugar

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SqlSugar is an open-source .NET ORM framework supporting multiple databases with high performance,...
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### Initialize JsonClient

Source: https://www.donet5.com/Home/Doc?typeId=2420

Setup the JsonClient with a SqlSugarClient connection configuration.

```csharp
JsonClient jsonToSqlClient = new JsonClient();
jsonToSqlClient.Context = new SqlSugarClient(new ConnectionConfig()
           {
               DbType = DbType.MySql,
               IsAutoCloseConnection = true,
        枭ConnectionString = "server=localhost;Database=db1;Uid=root;Pwd=123"
           });
```

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

### DateIsSameDay and DateIsSameByType Examples

Source: https://www.donet5.com/Home/Doc?typeId=2421

Examples for date comparison functions.

```csharp
var whereObj=  ObjectFuncModel.Create("DateIsSameDay", "CreateTime", "{DateTime}:2020-1-1");
          
var whereObj2 = ObjectFuncModel.Create("DateIsSameByType",
 "CreateTime", "{DateTime}:2020-1-1", "{string}:" +   DateType.Month );
```

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

### Initialize SqlSugarClient for MySql

Source: https://www.donet5.com/Home/Doc?typeId=1219

Basic setup for connecting to a MySql database using SqlSugarClient.

```csharp
 SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
 {
      DbType = DbType.MySql,
      ConnectionString ="server=localhost;Database=SqlSugar4xTest;Uid=root;Pwd=haosql",
      IsAutoCloseConnection = true
 });
 //个别特殊的数据库需要禁用Nvarchar(标题4)
```

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

### Install SqlSugarCore via NuGet

Source: https://www.donet5.com/Home/Doc?typeId=2368

Recommended NuGet package for SqlSugar.

```text
SqlSugarCore //建议最新
```

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

### ObjectFuncModel Parameter Examples

Source: https://www.donet5.com/Home/Doc?typeId=2421

Examples showing how to use fields, variables, and nested functions as parameters in ObjectFuncModel.

```csharp
/***字段参数***/
 ObjectFuncModel.Create("ToInt64","Id")
//sql：  Cast( [id] As  BigInt)

/***变量参数***/
 ObjectFuncModel.Create("ToInt64","{int}:1")
//sql：  Cast( @p As  BigInt) ; @p=1  DbType=Int

/***函数参数***/
 ObjectFuncModel.Create("ToInt64", ObjectFuncModel.Create("ToInt64","Id"))
//sql：  Cast(  Cast( Id  As  BigInt) As BigInt);  


/***综合用例***/
ObjectFuncModel.Create("GreaterThan", ObjectFuncModel.Create("AggregateAvg", "ID"), "{int}:1")
//用到了SqlFunc.GreaterThan嵌套SqlFunc.AggregateAvg函数
//sql：  avg([id])>@p (其中@p=1 并且 Dbtype=int)
```

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

### NuGet Installation Packages

Source: https://www.donet5.com/Home/Doc?typeId=2640

Required NuGet packages for Xugu database support.

```text
SqlSugarCore
SqlSugar.XuguCoreNew
```

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

### Nuget Package Installation

Source: https://www.donet5.com/Home/Doc?typeId=2437

Required packages for ClickHouse support in SqlSugar.

```text
SqlSugar.ClickHouseCore
SqlSugarCore
```

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

### Sqlite Table Creation with Descriptions

Source: https://www.donet5.com/Home/Doc?typeId=1222

Example of a SQL CREATE TABLE statement that includes comments for descriptions.

```sql
CREATE TABLE "CodeFirstUnitafa121"(
"Id" integer NOT NULL PRIMARY KEY AUTOINCREMENT /*编号*/ ,
"Name" datetime NOT NULL   DEFAULT (strftime('%Y-%m-%d %H:%M:%S', 'now', 'localtime')) /*时间*/,
"Name2" varchar(255) NOT NULL   DEFAULT '1'  ) /*姓名*/
```

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

### Initialize Database and Tables

Source: https://www.donet5.com/Home/Doc?typeId=1206

Basic commands to create a database if it does not exist and to initialize a table from a C# entity class.

```csharp
//建库：如果不存在创建数据库存在不会重复创建 createdb
db.DbMaintenance.CreateDatabase(); // 注意 ：Oracle和个别国产库需不支持该方法，需要手动建库 


//创建表：根据实体类CodeFirstTable1  (所有数据库都支持)    
db.CodeFirst.InitTables(typeof(CodeFirstTable1));//这样一个表就能成功创建了


//保护机质说明：如果不是sqlsugar建的表执行CodeFirst会报错看标题8

//实体定义看2.1
```

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

### Define MongoDB Entity Base Classes

Source: https://www.donet5.com/Home/Doc?typeId=2651

Examples of base classes for MongoDB entities using different primary key types. Requires SqlSugar.MongoDbCore 5.1.4.227 or higher for long, string, and Guid types.

```csharp
    public class MongoDbBase //ORM自带的基类
    {
        [BsonRepresentation(BsonType.ObjectId)]
        [SugarColumn(IsPrimaryKey =true,IsOnlyIgnoreInsert =true,ColumnName ="_id")]
        public string Id { get; set; }//ObjectId类型存储
    }
    public class MongoDbBaseLong//ORM自带的基类 SqlSugar.MongoDbCore 5.1.4.227+
    {
        [SqlSugar.SugarColumn(IsPrimaryKey = true, ColumnName = "_id")]
        public long Id { get; set; }//long类型可以用sqlsugar雪花ID插入
    }
    public class MongoDbBaseString//ORM自带的基类 SqlSugar.MongoDbCore 5.1.4.227+
    {
        [SqlSugar.SugarColumn(IsPrimaryKey = true, ColumnName = "_id")]
        public string Id { get; set; } //自定义string格式主键
    }
    public class MongoDbBaseGuid//ORM自带的基类  SqlSugar.MongoDbCore 5.1.4.227+
    {
        [SqlSugar.SugarColumn(IsPrimaryKey = true, ColumnName = "_id")]
        public Guid Id { get; set; }  //自定义guid类型主键
    }
```

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

### ContainsArray Function Example

Source: https://www.donet5.com/Home/Doc?typeId=2421

Examples of using ContainsArray for IN and NOT IN SQL clauses.

```csharp
var whereObj=ObjectFuncModel.Create("ContainsArray", "{int}:" + db.Utilities.SerializeObject(new int[] { 1, 2 ,3}),"UserId")

 //UserId not in(1,2,3)
 IFuncModel func = ObjectFuncModel.Create("ContainsArray", "{int}:[1,2,3]", "userid");
 func = ObjectFuncModel.Create("format","not", "(", func, ")");
```

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

### QuestDB SQL Query Examples

Source: https://www.donet5.com/Home/Doc?typeId=2434

Example SQL queries for testing performance on large datasets in QuestDB.

```sql
//测试用例1： LIKE 1亿多取一条 用了1秒
select * from pos where id ~ 'OQHFDQTJTJJQEEEZ' //Like

//测试用例2：按天分表 所有数据进行汇总 接近2亿数据汇总 用了9秒左右
select  sum(price),side from 'trades' where price>100 group by side

//测试用例3：按天分表 所有数据进行汇总 接近2亿进行Count 用了2秒 （关系型数据库要20分钟以上）
select count(1) from 'trades'
```

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

### OceanBase MySql模式 Hints配置

Source: https://www.donet5.com/Home/Doc?typeId=2564

使用Optimizer Hints在SQL语句中改变执行计划。

```csharp
db.Queryable<Order>().Hints("/*+ ... */").ToList();
```

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

### IIF Conditional Function Example

Source: https://www.donet5.com/Home/Doc?typeId=2421

Example of using the IIF function to create a CASE WHEN SQL expression.

```csharp
new ObjectFuncModel()
{
    FuncName = "IIF",
    Parameters = new List<object>{
       new ObjectFuncModel(){
        FuncName="Equals",//嵌套了一个等于函数
        Parameters=new List<object>{ "UserId", "{int}:0" }
       },"UserId","{int}:1"
     }

}
```

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

### 配置达梦数据库 Docker 分页兼容模式

Source: https://www.donet5.com/Home/Doc?typeId=1229

在 Docker 环境下使用达梦数据库时，若分页功能无效，需在 ConnectionConfig 中配置 MoreSettings 以启用 MySql 兼容模式。

```csharp
SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
{
    DbType = DbType.Dm,
    IsAutoCloseConnection = true,
    ConnectionString = Config.ConnectionString, 
     MoreSettings=new ConnMoreSettings()
     {
       //SqlSugarCore 5.1.4.157-preview09+版本支持
       DatabaseModel=SqlSugar.DbType.MySql //启用达梦mysql模式分页的兼容
    }
});
```

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

### Registering and Using Custom SplitTableService

Source: https://www.donet5.com/Home/Doc?typeId=1201

Demonstrates how to apply the custom service using attributes (recommended for version 5.1.4.78+) or global configuration, and how to insert data into split tables.

```csharp
//推荐写法：高版本支持了特性使用自定义分表 5.1.4.78
[SplitTable(SplitType._Custom01,typeof(WordSplitService))]

//老版本写法：不推荐 
db.CurrentConnectionConfig.ConfigureExternalServices.SplitTableService =new WordSplitService();


//插入数据
db.Insertable(new WordTestTable(){CreateTime=DateTime.Now,Name="BC"}).SplitTable().ExecuteReturnSnowflakeId();
db.Insertable(new WordTestTable(){CreateTime=DateTime.Now,Name="AC"}).SplitTable().ExecuteReturnSnowflakeId();
db.Insertable(new WordTestTable(){CreateTime=DateTime.Now,Name="ZBZ"}).SplitTable().ExecuteReturnSnowflakeId();　　
```

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

### 安装 Furion.SqlSugar.Template.Mvc 脚手架

Source: https://www.donet5.com/Home/Doc?typeId=1226

使用 dotnet new 命令安装 Furion 提供的 SqlSugar MVC 模板。安装后即可通过该模板创建项目，并配置 appsettings.json 中的连接字符串以运行。

```bash
dotnet new --install Furion.SqlSugar.Template.Mvc::3.8.7
//最新版本可以通过Nuget搜索去看版本号
```

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

### Multi-condition join query example

Source: https://www.donet5.com/Home/Doc?typeId=2421

Example of a join query with multiple conditions using ObjectFuncModel.Create and supported operators.

```APIDOC
## Multi-condition join query example

### Description
Example of a join query with multiple conditions using ObjectFuncModel.Create and supported operators.

### Method
AddJoinInfo + Select

### Example
```csharp
var onList = ObjectFuncModel.Create("Format", "d.orderid", ">", "o.id", "&&", "o.id", ">", "{int}:1");
var list = db.Queryable<object>()
  .AS("order", "o")
  .AddJoinInfo("orderdetail", "d", onList, JoinType.Left)
  .Select(SelectModel.Create(new SelectModel() { FiledName = "o.id", AsName = "id" }))
  .ToList();
```

### Generated SQL
```sql
SELECT `o`.`id` AS `id` FROM `order` o Left JOIN `orderdetail` d ON `d`.`orderid` > `o`.`id` And `o`.`id` > @p0
```

### Supported operators
">", ">=", "<", "<=", "(", ")", "=", "||", "&&", "&", "|", "null", "is", "isnot", "like", "nolike", "+", "-", "*", "/", "%"

### Functions in expressions
You can use functions like "{SqlFunc_AggregateMin:["id"]}" inside the expression.

```

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

### Multi-database join query example

Source: https://www.donet5.com/Home/Doc?typeId=2421

Example of a join query using AddJoinInfo with a function model and SelectModel, supporting multiple databases.

```APIDOC
## Multi-database join query example

### Description
Example of a join query using AddJoinInfo with a function model and SelectModel, supporting multiple databases.

### Method
AddJoinInfo + Select

### Example
```csharp
db.Queryable<object>().AS("order", "o")
  .AddJoinInfo("orderdetail", "d", ObjectFuncModel.Create("Equals", "d.orderid", "o.id"), JoinType.Left)
  .Select(new List<SelectModel>(){
    new SelectModel() { AsName = "id", FiledName = "o.id" }
  })
  .ToList();
```

### Generated SQL
```sql
SELECT `o`.`id` AS `id` FROM `Order` o Left JOIN `orderdetail` d ON (`d`.`orderid` = `o`.`id`)
```

```

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

### Configure SqlSugarClient with RazorService

Source: https://www.donet5.com/Home/Doc?typeId=1207

Demonstrates how to initialize a SqlSugarClient with a custom RazorService and trigger class file generation using a Razor template.

```csharp
    SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
    {
                ConnectionString = Config.ConnectionString,
                DbType = DbType.SqlServer,
                IsAutoCloseConnection = true,
                ConfigureExternalServices = new ConfigureExternalServices()
                {
                    RazorService = new RazorService()//新建一个RazorService类 
                }
     });

    var templte = RazorFirst.DefaultRazorClassTemplate;//这个是自带的，这个模版可以修改
    db.DbFirst.UseRazorAnalysis(templte).CreateClassFile("c:\\Demo\\Razor\\");
```

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

### Configure and Use SqlSugar.IOC

Source: https://www.donet5.com/Home/Doc?typeId=2247

Demonstrates how to initialize SqlSugar services with IocConfig, configure AOP logging, and perform database queries using DbScoped.

```csharp
 // 10秒入门
 SugarIocServices.AddSqlSugar(new IocConfig()
 {
    //ConfigId="db01"  多租户用到
   ConnectionString = "server=.;uid=sa;pwd=sasa;database=SQLSUGAR4XTEST",
   DbType = IocDbType.SqlServer,
   IsAutoCloseConnection = true//自动释放
 }); //多个库就传List<IocConfig>
 
 //配置参数
 SugarIocServices.ConfigurationSugar(db =>
 {
     db.Aop.OnLogExecuting = (sql, p) =>
     {
       Console.WriteLine(sql);
     };
     //设置更多连接参数
     //db.CurrentConnectionConfig.XXXX=XXXX
     //db.CurrentConnectionConfig.MoreSettings=new ConnMoreSettings(){}
     //二级缓存设置
     //db.CurrentConnectionConfig.ConfigureExternalServices = new ConfigureExternalServices()
      //{
         // DataInfoCacheService = myCache //配置我们创建的缓存类
      //}
     //读写分离设置
     //laveConnectionConfigs = new List<SlaveConnectionConfig>(){...}
     
     /*多租户注意*/
     //单库是db.CurrentConnectionConfig 
     //多租户需要db.GetConnection(configId).CurrentConnectionConfig 
 });
 
 //CodeFirst请写这儿，与SugarIocServices.AddSqlSugar平级
 //DbScoped.SugarScope.CodeFirst<T>();
 
 
  //注入后就能所有地方使用
  DbScoped.SugarScope.Queryable<UserOrgMapping>().Where(it=>it.Id>0).ToList() //1.7版本支持
  DbScoped.Sugar.Queryable<UserOrgMapping>().Where(it=>it.Id>0).ToList()

  //DbScoped.SugarScope=SqlSugarScope (推荐)
  //DbScoped.Sugar=SqlSugarClient
```

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

### Disable char(36) GUID conversion

Source: https://www.donet5.com/Home/Doc?typeId=1219

Add this setting to the connection string to prevent the driver from treating char(36) strings as GUIDs.

```text
//连接字符串加上，如果没有效果可以百度一下，我这个没有测试
OldGuids=True
```

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

### Simple join query example

Source: https://www.donet5.com/Home/Doc?typeId=2421

Example of a simple join query using raw SQL string for the ON condition. Not suitable for code encapsulation and has poor multi-database compatibility.

```APIDOC
## Simple join query example

### Description
Example of a simple join query using raw SQL string for the ON condition. Not suitable for code encapsulation and has poor multi-database compatibility.

### Method
AddJoinInfo + Select

### Example
```csharp
var list = db.Queryable<object>().AS("order", "o")
  .AddJoinInfo("table1", "a", "a.id=o.id and a.id>1", JoinType.Left)
  .Select("a.*").ToList();
```

```

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

### Initialize Tables for Multi-Tenancy

Source: https://www.donet5.com/Home/Doc?typeId=1206

Initialize tables using attributes to identify specific databases in a multi-tenant environment.

```csharp
//根据特性标识哪个库 (需要高版本才支持)
db.CodeFirst.InitTablesWithAttr(new[] { typeof(UserInfo001), typeof(UserInfo002) });
```

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

### Multi-tenant Configuration

Source: https://www.donet5.com/Home/Doc?typeId=1183

Initialize SqlSugarClient with a list of ConnectionConfig objects to support multiple databases.

```csharp
SqlSugarClient db = new SqlSugarClient(new List<ConnectionConfig>()
{
  new ConnectionConfig()
  { ConfigId="0", DbType=DbType.SqlServer,ConnectionString=..,IsAutoCloseConnection=true},
  
  new ConnectionConfig()
  { ConfigId="1", DbType=DbType.MySql,ConnectionString=..,IsAutoCloseConnection=true}
});
```

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

### 配置Docker版达梦分页兼容

Source: https://www.donet5.com/Home/Doc?typeId=1229

针对Docker安装的达梦数据库（MySQL模式），需配置DatabaseModel以确保分页功能正常。支持版本为SqlSugarCore 5.1.4.157-preview09及以上。

```csharp
SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
{
    DbType = DbType.Dm,
    IsAutoCloseConnection = true,
    ConnectionString = Config.ConnectionString, 
     MoreSettings=new ConnMoreSettings()
     {
       //SqlSugarCore 5.1.4.157-preview09+版本支持
       DatabaseModel=SqlSugar.DbType.MySql //启用达梦mysql模式分页的兼容
     }
});
```

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

### Initialize SqlSugarClient for Gbase

Source: https://www.donet5.com/Home/Doc?typeId=2440

Configuration required to initialize the SqlSugarClient for Gbase, including custom assembly registration.

```csharp
//程序启动时只执行一次
InstanceFactory.CustomAssemblies =
new System.Reflection.Assembly[] { typeof(GBaseProvider).Assembly };

//创建db对象和其他库一样用法
SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
 {
    ConnectionString = "上面的字符串",
    DbType = DbType.GBase, //GBase
    IsAutoCloseConnection = true 
  },
  db=>{
        //aop 
   
   });
```

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

### Docker Installation Command

Source: https://www.donet5.com/Home/Doc?typeId=2437

Command to pull the latest ClickHouse server image.

```bash
docker pull yandex/clickhouse-server
```

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

### Initialize Xugu Database Connection

Source: https://www.donet5.com/Home/Doc?typeId=2640

Register the assembly and configure the SqlSugarClient for Xugu. The connection string includes parameters like IP, DB, User, PWD, Port, and character set.

```csharp
//注册DLL写在程序启动时
InstanceFactory.CustomAssemblies = new System.Reflection.Assembly[] {
    typeof(XuguProvider).Assembly
};



SqlSugarClient db = new SqlSugarClient(new ConnectionConfig()
{
    ConnectionString = "IP=111.123.17;DB=HOUSE;User=SYSDBA;PWD=abc;Port=5138;AUTO_COMMIT=on;CHAR_SET=UTF8",//CHAR_SET=GBK
    DbType = SqlSugar.DbType.Xugu,
    IsAutoCloseConnection = true,
    //ConfigureExternalServices = new ConfigureExternalServices() { SqlFuncServices = SqlFuncCustom.Methods }
},
db => {
    db.Aop.OnLogExecuting = (sql, pars) =>
    {

        Console.WriteLine(SqlSugar.UtilMethods.GetNativeSql(sql, pars));
    };
});

//CRUD
 db.Insertable(list).ExecuteCommand(); 
 var list = db.Queryable<MY_USER>().ToList();
 db.Updateable(list).ExecuteCommand();
 db.Deleteable(list).ExecuteCommand();
```

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

### Get ExpressionContext from DB Queryable

Source: https://www.donet5.com/Home/Doc?typeId=2359

Retrieve the ExpressionContext directly from the Queryable object.

```csharp
Expression<Func<UserInfo002, bool>> exp = it => it.UserId==1;
QueryBuilder q = db.Queryable<object>().QueryBuilder;
var sql=q.GetExpressionValue(exp, ResolveExpressType.WhereSingle).GetResultString();
var parameters = q.Parameters;
```

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

### Change Repository Dynamically

Source: https://www.donet5.com/Home/Doc?typeId=1228

Demonstrates how to obtain an external repository from an existing one.

```csharp
//获取外部仓储
var itemDal=_userRepository.ChangeRepository<Repository<OrderItem>>();
var orderDal=_userRepository.ChangeRepository<Repository<Order>>();
//base.Change<OrderItem>()这种写法与上面区别在于只能用ORM中的方法，没办法使用扩展类中的方法
```

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

### StartsWith Function

Source: https://www.donet5.com/Home/Doc?typeId=1190

Performs a LIKE query for strings starting with a specific value.

```csharp
SqlFunc.StartsWith(object thisValue, string parameterValue) //查询字符串开头
```

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

### Delete Data from MongoDB

Source: https://www.donet5.com/Home/Doc?typeId=2651

Examples of deleting records by primary key array or by entity.

```csharp
//根据主键岀队
string [] ids= [...]
db.Deleteable<Student>().In(ids).ExecuteCommandAsync()

//根据实体删除,实体要有主键 
var delrow = db.Deleteable(data).ExecuteCommand();
```

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

### SQL Server Connection Strings

Source: https://www.donet5.com/Home/Doc?typeId=1218

Examples of connection strings for different SqlSugar versions. Newer versions require Encrypt=True and TrustServerCertificate=True.

```text
//SqlSugar或者SqlSugarCore 1.1.4.68以下版本
server=.;uid=sa;pwd=haosql;database=SQLSUGAR4XTEST

//SqlSugarCore 5.1.4.169上以上版本
server=.;uid=sa;pwd=haosql;database=SQLSUGAR4XTEST;Encrypt=True;TrustServerCertificate=True;
```

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

### One-to-Many Query Examples

Source: https://www.donet5.com/Home/Doc?typeId=1188

Demonstrates various ways to query one-to-many relationships, including filtering, sorting, and selecting specific fields.

```csharp
//例1：简单用法
var list = db.Queryable<StudentA>()
.Includes(x => x.Books)
.ToList();

//例2：支持Any和Count  对主表进行过滤  (子对象过滤看下面)
var list = db.Queryable<StudentA>()
.Includes(x => x.Books)
.Where(x => x.Books.Any())
//带条件的
//.Where(x => x.Books.Any(z=>z.Name=="jack")))
.ToList();

//例3: 没有Includes也可以使用过滤
var list2 = db.Queryable<StudentA>()
.Where(x => x.Books.Any())//Any中可以加条件 Any(z=>z.BookId==1)
.ToList();             


//例4 Where子对象进行排序和过滤  (支持WhereIF)
var list = db.Queryable<StudentA>()
  .Includes(x => x.Books.Where(y => y.BookId > 0).OrderBy(y => y.BookId).ToList())
  .ToList();
  
//例5 主表+子表都过滤
var list = db.Queryable<StudentA>()
.Includes(x => x.Books.Where(it=>it.Name=="jack").ToList())//只过滤子表
.Where(x => x.Books.Any(z=>z.Name=="jack")))
.ToList();
  
//例6：Select指定字段
var list= db.Queryable<StudentA>()
           .Includes(x => x.Books.Select(z=>new BookA() { Names = z.Names }).ToList()) 

//例7：Select多层级  (结构：StudentAt->books->BookItems)       
var list= db.Queryable<StudentA>()
     .Includes(x => x.Books.Select(z=>new BookA(){Names=z.Name}.ToList(),it=>BookItems)) 
    .ToList();、//Includes中的Select只能是字段 ，不能导航对象           
           
           
//例8：OrderBy指定字段 （Skip Take可以分页）
var list= db.Queryable<StudentA>()
           .Includes(x => x.Books.OrderBy(z=>z.Id).ToList()) 
           .ToList();
           
//例9：Take取前几条
var list= db.Queryable<StudentA>()
           .Includes(x => x.Books.Take(10).ToList()) 
           .ToList();                         
           
           
//例10：DTO支持进行了强化   
看标题2.7         
           
           
//例11：一对多后还可用追加字段映射MappingField  如果以前是1个字关联，现在追加后就成了1+1       
db.Queryable<StudentA>().Includes(x => x.Books.MappingField(z=>z.字段,()=>x.字段).ToList() )
               .ToList();
//MappingField 和 Where区别
//MappingField MappingField用来指定2个对象的关系，Where只能当前表过滤不能和主表进行关联 
//MappingField 可以多个也可以和Where一起始用
```

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

### TDengine Connection String Format

Source: https://www.donet5.com/Home/Doc?typeId=2566

Example of a standard TDengine connection string for SqlSugar.

```text
Host=localhost;Port=6030;Username=root;Password=taosdata;Database=power
//默认是毫秒，要微秒等看下面有介绍
```

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

### Nested Query Resulting SQL

Source: https://www.donet5.com/Home/Doc?typeId=2354

The SQL output generated by the nested query examples.

```sql
SELECT t.* FROM  (SELECT [Id],[Name],[Price],[CreateTime],[CustomId] FROM [Order] ) t
```

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

### Enable AOT and Initialize SqlSugarClient

Source: https://www.donet5.com/Home/Doc?typeId=2574

Enable AOT and initialize the SqlSugarClient. Note that you should use a new instance for each operation rather than a singleton pattern.

```csharp
//启用AOT 程序启动执行一次就好了
StaticConfig.EnableAot = true;

//用SqlSugarClient每次都new,不要用单例模式 
var db = new SqlSugarClient(new ConnectionConfig()
   {
       IsAutoCloseConnection = true,
       DbType = DbType.Sqlite,
       ConnectionString = "datasource=demo.db" 

   },
   it =>
   {
       // Logging SQL statements and parameters before execution
       // 在执行前记录 SQL 语句和参数
       it.Aop.OnLogExecuting = (sql, para) =>
       {
           Console.WriteLine(UtilMethods.GetNativeSql(sql, para));
       };
   });
   return db;
```

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

### SqlSugar Delete Event Handling

Source: https://www.donet5.com/Home/Doc?typeId=1204

Example of using DataExecuting for entity deletion operations.

```csharp
 db.Aop.DataExecuting = (oldValue, entityInfo) =>
 {
      /*** 删除生效 （只有行级事件） ***/       
      if (entityInfo.OperationType == DataFilterType.DeleteByObject)
      {
         //entityInfo.EntityValue 拿到所有实体对象
      }
      
      //可以写多个IF
 }
 
 /***只能是实体删除***/
 db.Deleteable(List<T>).ExecCommand();//实体集合有效
 db.Deleteable(T).ExecCommand();//实体有效
```

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

### 配置 Optimizer Hints

Source: https://www.donet5.com/Home/Doc?typeId=2565

使用 Hints 方法在 SQL 语句中注入优化器提示以改变执行计划。

```csharp
db.Queryable<Order>().Hints("/*+ ... */").ToList();
```

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

### Execute SQL Query with Pagination

Source: https://www.donet5.com/Home/Doc?typeId=1180

Demonstrates how to execute a raw SQL query, order the results, and perform pagination using SqlSugar.

```csharp
db.SqlQueryable<Student>("select * from student").OrderBy("id asc").ToPageList(1, 2,ref total)
```

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

### Install TDengine NuGet Packages

Source: https://www.donet5.com/Home/Doc?typeId=2566

Required NuGet packages for using TDengine with SqlSugar.

```text
SqlSugar.TDengineCore
SqlSugarCore
```

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

### Perform GaussDB Queries

Source: https://www.donet5.com/Home/Doc?typeId=2438

Examples for querying all records, filtering by condition, and performing paginated queries.

```csharp
db.Queryable<Student>().ToList()//查询所有
db.Queryable<Student>().Where(it=>it.Id==1).ToList()//根据条件查询
//分页  int pageIndex = 1; // pageindex是从1开始的不是从零开始的
int pageSize = 20;
int totalCount=0;
//单表分页
var page = db.Queryable<Student>().ToPageList(pageIndex, pageSize, ref totalCount);
```

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

### 配置 InitKeyType 兼容旧版本

Source: https://www.donet5.com/Home/Doc?typeId=1216

对于 5.0.2 以下版本升级，需显式设置 InitKeyType 为 Systemtable 以保持与旧版本默认行为一致。

```csharp
 DbType = SqlSugar.DbType.SqlServer,
 ConnectionString = Config.ConnectionString,
 InitKeyType = InitKeyType.Attribute,//这个默认值换了，如果以前没有设置需要改成Systemtable
 IsAutoCloseConnection = true,
```

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

### Class-based Call Pattern

Source: https://www.donet5.com/Home/Doc?typeId=2352

Example of accessing a static SqlSugarScope instance from a separate DbContext class.

```csharp
    public class TestManager 
    {
        public List<Order> Add()
        {
            return DbContext.Db.Queryable<Order>().ToList();
        }

    }
    public class DbContext //如果是泛型类 Db要扔到外面 ,DbContext<T>.Db会导致产生多个实例
    { 
            //这里要public 
        public static SqlSugarScope Db = new SqlSugarScope(new ConnectionConfig()
        {
            DbType = SqlSugar.DbType.SqlServer,
            ConnectionString = Config.ConnectionString,
            IsAutoCloseConnection = true
        },
         db => {
              //单例参数配置，所有上下文生效
              db.Aop.OnLogExecuting = (s, p) =>
              {
                  Console.WriteLine(s);
              };
         });
    }
```

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

### 实现动态多数据库模式

Source: https://www.donet5.com/Home/Doc?typeId=2246

在运行时通过AddConnection动态添加数据库连接，适用于用户或企业对应独立数据库的场景。

```csharp
 //当前上下文不存在则添加 
 if(!db.IsAnyConnection(configId))
    //添加一个db到当前上下文 (Add部分不线上下文不会共享)
    db.AddConnection(new ConnectionConfig(){
                DbType = SqlSugar.DbType.SqlServer,
                ConfigId = "1",//设置库的唯一标识
                IsAutoCloseConnection = true,
                ConnectionString = Config.ConnectionString2 });
                
  var currentDb=db.GetConnection(configId);//获取当前上下文存在的db   
  //和主库AOP不共享需
  //currentDb.Aop.xxx         
                
 //单例SqlSugarScope中用AddConnection和IsAnyConnection多用户不会相互影响，不会共享
```

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

### Insert and Query Geometry Data

Source: https://www.donet5.com/Home/Doc?typeId=1218

Example code for inserting and querying geometry data in SqlServer.

```csharp
db.Insertable(new UnitGe() { geometry1 = "POINT (20 180)" }).ExecuteCommand();
var gelist=db.Queryable<UnitGe>().Select(it=>new { geometry1 = it.geometry1.ToString()}).ToList();
```
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