EF提供的3中查询方式

1. Linq to Entities

using (TestEntities te = new TestEntities())
{
    var user = from a in te.User
               where a.UserDepartment.UserDepartment_name == "經理部"
               orderby a.User_id
               select a;
}

lambda方式

using (TestEntities te = new TestEntities())
{
    var user = te.User.Where(a => a.UserDepartment.UserDepartment_name == "經理部")
                      .OrderBy(a => a.User_id)
                      .Select(a => a);
}

2. Query Builder Mothed

using (TestEntities te = new TestEntities())
{
    var user = te.User.Where("it.UserDepartment.UserDepartment_name == "經理部"")
                      .OrderBy("it.User_id");                                 
}

3. Entity SQL Language 

using (TestEntities te = new TestEntities())
{
    string entitySQL = "SELECT Value a FROM User as a";
    entitySQL += " WHERE a.UserDepartment.UserDepartment_name == "經理部"";
    entitySQL += " Order by a.User_id";
    var user = te.CreateQuery<User>(entitySQL);
}

比较

	Linq to Entities	Query Builder Mothed	Entity SQL Language
智能提示	０	Ｘ	Ｘ
设计期除错	Ｏ	Ｘ	Ｘ
动态查询	Ｘ	Ｏ	Ｏ
对Provider产生的SQL语法控制	一般	較好	最好
支持的函数式	一般	多	多
开发速度	最佳	一般	一般