这是LINQ-to-SQL的示例吗? [英] Is this an example of LINQ-to-SQL?

问题描述

我用SQL CE数据库制作了一个WPF小应用程序.

我用LINQ构建了以下代码来从数据库中获取数据，这非常容易.所以我认为这必须是LINQ-to-SQL".

然后，我做了添加项目"并添加了"LINQ-to-SQL类" .dbml文件，将表拖到了对象关系设计器"上，但是它说:所选对象使用了不受支持的数据提供程序."

因此，我质疑以下代码是否实际上是LINQ-to-SQL，因为它确实允许我从我的SQL CE数据库文件访问数据，但是正式似乎不支持"LINQ-to-SQL" SQL CE.

那么下面的"LINQ-to-SQL"是否正确?

using System.Linq;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Windows;

namespace TestLinq22
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            MainDB db = new MainDB(@"Data Source=App_Data\Main.sdf");
            var customers = from c in db.Customers
                            select new {c.FirstName, c.LastName};
            TheListBox.ItemsSource = customers;
        }
    }

    [Database(Name = "MainDB")]
    public class MainDB : DataContext
    {
        public MainDB(string connection) : base(connection) { }
        public Table<Customers> Customers;
    }

    [Table(Name = "Customers")]
    public class Customers
    {
        [Column(DbType = "varchar(100)")]
        public string FirstName;

        [Column(DbType = "varchar(100)")]
        public string LastName;
    }

}

解决方案

此msdn文章指出，尽管LINQ to SQL运行时支持sdf，但设计器不支持sdf.

引用:

• LINQ to SQL运行时和SQLMetal命令行工具支持SQL Server Compact 3.5.
• 对象关系设计器不支持SQL Server Compact 3.5.

I made a little WPF application with a SQL CE database.

I built the following code with LINQ to get data out of the database, which was surprisingly easy. So I thought "this must be LINQ-to-SQL".

Then I did "add item" and added a "LINQ-to-SQL classes" .dbml file, dragged my table onto the Object Relational Designer but it said, "The selected object uses an unsupported data provider."

So then I questioned whether or not the following code actually is LINQ-to-SQL, since it indeed allows me to access data from my SQL CE database file, yet officially "LINQ-to-SQL" seems to be unsupported for SQL CE.

So is the following "LINQ-to-SQL" or not?

using System.Linq;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Windows;

namespace TestLinq22
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            MainDB db = new MainDB(@"Data Source=App_Data\Main.sdf");
            var customers = from c in db.Customers
                            select new {c.FirstName, c.LastName};
            TheListBox.ItemsSource = customers;
        }
    }

    [Database(Name = "MainDB")]
    public class MainDB : DataContext
    {
        public MainDB(string connection) : base(connection) { }
        public Table<Customers> Customers;
    }

    [Table(Name = "Customers")]
    public class Customers
    {
        [Column(DbType = "varchar(100)")]
        public string FirstName;

        [Column(DbType = "varchar(100)")]
        public string LastName;
    }

}

解决方案

This msdn article notes that while sdf is supported by the LINQ to SQL runtime, it is not supported by the designer.

To Quote:

• The LINQ to SQL runtime and the SQLMetal command-line tool support SQL Server Compact 3.5.
• The Object Relational Designer does not support SQL Server Compact 3.5.

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