兩個資料表如果存在多對多的關連，勢必需要有第三個資料表（關連資料表）記載這項關係，最簡單的關連資料表只需2個欄位，分別存放所關連到資料表的主鍵欄位值。這樣的需求條件下，Kuick提供一個內鍵的功能（多對多關連服務， Kuick.BuiltIn.Mapping），提供建立任意兩個資料表之間的關連，甚至是資料表自我關連亦可。
請下載今天的範例程式碼 Labs-2013-10-04

1. 「多對多關連服務」資料結構
多對多關連服務需要記錄任意兩個Entity的任意兩筆資料的關連，先從下圖的資料結構來看。

T_MAPPING資料表依據兩個Entity的Class名稱，區分成PRE_ORDER（前序）與POST_ORDER（後序），分別記錄Entity名稱、鍵值與序次
例如：以EmployeeEntity與RoleEntity為例，EmployeeEntity其中一筆資料鍵值為kevin，RoleEntity其中一筆資料鍵值為manager。
前序 -- EmployeeEntity
後序 -- RoleEntity
如果kevin與manager如果建立關連，T_MAPPING資料表將增加一筆資料

2.「多對多關連服務」介面定義
「多對多關連服務」介面定義在Kuick.Data組件裡，實作於Kuick.Builtin.Mapping組件。

int Count<TContainer, TMember>(string containerID)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
bool Exists<TContainer, TMember>(string containerID, string memberID)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
Result Add<TContainer, TMember>(string containerID, params string[] memberIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
Result Remove<TContainer, TMember>(string containerID, params string[] memberIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
Result Clear<TContainer, TMember>(string containerID)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
void Sorting<TContainer>(params string[] ids)
	where TContainer : class, IEntity, new();
 
void Sorting<TContainer, TMember>(string containerID, params string[] memberIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
List<TMember> Get<TContainer, TMember>(params string[] containerIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
List<TMember> Get<TContainer, TMember>(
	Func<Sql<TMember>, Sql<TMember>> sqlIntercepter,
	params string[] containerIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
List<string> AllMemberIDs<TContainer, TMember>(string containerID)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
Sql<TMember> GetSql<TContainer, TMember>(params string[] containerIDs)
	where TContainer : class, IEntity, new()
	where TMember : class, IEntity, new();
 
int Count(
	string containerEntityName,
	string memberEntityName,
	string containerID);
 
bool Exists(
	string containerEntityName,
	string memberEntityName,
	string containerID, 
	string memberID);
 
Result Add(
	string containerEntityName,
	string memberEntityName,
	string containerID,
	params string[] memberIDs);
Result Remove(
	string containerEntityName,
	string memberEntityName,
	string containerID,
	params string[] memberIDs);
Result Clear(
	string containerEntityName,
	string memberEntityName,
	string containerID);
 
void Sorting(
	string containerEntityName,
	params string[] ids);
 
void Sorting(
	string containerEntityName,
	string memberEntityName,
	string containerID, 
	params string[] memberIDs);
 
List<IEntity> Get(
	string containerEntityName,
	string memberEntityName,
	params string[] containerIDs);
List<IEntity> Get(
	string containerEntityName,
	string memberEntityName,
	Func<Sql, Sql> sqlIntercepter,
	params string[] containerIDs);
List<string> AllMemberIDs(
	string containerEntityName,
	string memberEntityName,
	string containerID);

3. 在EmployeeEntity與RoleEntity裡，增加對應關連
EmployeeEntity裡，增加所屬角色集合

private List<RoleEntity> _Roles;
public List<RoleEntity> Roles
{
	get
	{
		if(null == _Roles) {
			_Roles = Mapping<RoleEntity>().Get();
		}
		return _Roles;
	}
}

RoleEntity裡，增加成員集合

private List<EmployeeEntity> _Employees;
public List<EmployeeEntity> Employees
{
	get
	{
		if(null == _Employees) {
			_Employees = Mapping<EmployeeEntity>().Get();
		}
		return _Employees;
	}
}