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Linq To Sql CRUD操作示例

2012-04-24 10:23 429 查看
　　昨天简要的看了一下Linq To Sql 的操作方式，写了一个简单的CRUD操作的例子。去掉繁琐的理论，直接贴代码。【源代码下载】

　　我是新建了一个本地数据库，数据库字段如下：



根据这个结构，设计了一个实体类Book：

public class Book
{
/// <summary>
/// 图书ID
/// </summary>
[Column(IsPrimaryKey=true,DbType=("bigint"), IsDbGenerated=true)]
public Int64 bId { get; set; }
/// <summary>
/// 图书名称
/// </summary>
[Column]
public string Title { get; set; }
/// <summary>
/// 单价
/// </summary>
[Column(DbType = "float")]
public float Price { get; set; }
/// <summary>
/// 作者
/// </summary>
[Column]
public string Author { get; set; }
/// <summary>
/// ISBN号
/// </summary>
[Column]
public string ISBN { get; set; }
/// <summary>
/// 记录的版本号
/// </summary>
[Column(DbType = "rowversion", IsVersion=true)]
public byte[] Stamp { get; set; }
}

下面就是对它的CRUD操作：

　　　　　#region Linq To Sql [CRUD操作]

private static void LinqToSql_Select()
{
DataContext context = new DataContext(string.Format(@"Data Source={0}DB.sdf", AppDomain.CurrentDomain.BaseDirectory));
context.Log = Console.Out;  //输出Sql的执行过程，方便跟踪调试

var result = from book in context.GetTable<Book>()
where book.Price > 50 && book.Title.Contains("C#")
orderby book.Price descending
select book;

Console.WriteLine(result.Count());

Console.WriteLine("单价大于50元的书：");
foreach (var item in result)    //在遍历的时候，才正真的去执行查询
{
Console.WriteLine(item.Title);
}
}

private static void LinqToSql_Insert()
{
DataContext context = new DataContext(string.Format(@"Data Source={0}DB.sdf", AppDomain.CurrentDomain.BaseDirectory));
context.Log = Console.Out;  //输出Sql的执行过程，方便跟踪调试

ITable books = context.GetTable<Book>();

Book book = new Book() { Title = "C#高级编程", Author = "Wrox", ISBN = "1235=23-233", Price = 138 };
books.InsertOnSubmit(book);
context.SubmitChanges();

Console.WriteLine(book.bId);
}

private static void LinqToSql_Update()
{
DataContext context = new DataContext(string.Format(@"Data Source={0}DB.sdf", AppDomain.CurrentDomain.BaseDirectory));
context.Log = Console.Out;  //输出Sql的执行过程，方便跟踪调试

var books = from b in context.GetTable<Book>()
where b.bId == 5
select b;

Book book = books.First<Book>();
book.Title = "C#高级编程（第五版）";

context.SubmitChanges();
}

private static void LinqToSql_Delete()
{
DataContext context = new DataContext(string.Format(@"Data Source={0}DB.sdf", AppDomain.CurrentDomain.BaseDirectory));
context.Log = Console.Out;  //输出Sql的执行过程，方便跟踪调试

Table<Book> books = context.GetTable<Book>();

var query = from b in books
where b.bId == 5
select b;
Book book = query.First<Book>();

books.DeleteOnSubmit(book);
context.SubmitChanges();
}

#endregion

                        
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