步步为营VS 2008 + .NET 3.5(13) - DLINQ(LINQ to SQL)之用户自定义函数、在不同的DataContext之间做更新、缓存、获取信息、数据加载选项和延迟加载

作者：webabcd

介绍
以Northwind为示例数据库，DLINQ(LINQ to SQL)之调用标量值用户自定义函数；调用表值用户自定义函数；使用数据加载选项加载数据；相关信息的获取；字段的延迟加载；在不同的DataContext之间做更新；缓存

示例
Others.aspx.cs

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Linq;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Xml.Linq;

using DAL;

public partial class LINQ_DLINQ_Others : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

// 调用标量值用户自定义函数

Call_HelloFunctionScalar();

// 调用表值用户自定义函数

Call_HelloFunctionTable();

// 不使用数据加载选项

DataLoadOptions_Original();

// 使用数据加载选项加载数据

DataLoadOptions_LoadWith();

// 使用数据加载选项加载数据，并且限制所要加载的数据

DataLoadOptions_AssociateWith();

// 相关信息的获取

GetInfo();

// 字段的延迟加载

DelayLoaded();

// 在不同的DataContext之间做更新

IsVersion();

// 缓存

ShowCache();

}

调用标量值用户自定义函数

ALTER FUNCTION dbo.fnHelloFunctionScalar

(

@param nvarchar(100)

)

RETURNS nvarchar(200)

BEGIN

RETURN 'Hello:' + @param

END

/// <summary>

/// 调用标量值用户自定义函数

/// </summary>

void Call_HelloFunctionScalar()

{

NorthwindDataContext ctx = new NorthwindDataContext();

result.InnerHtml += ctx.HelloFunctionScalar("webabcd");

result.InnerHtml += " ";

}

运行结果
Hello:webabcd

调用表值用户自定义函数

ALTER FUNCTION dbo.fnHelloFunctionTable

(

@ID int,

@name nvarchar(100)

)

RETURNS @tbl TABLE ([ID] int, [Name] nvarchar(100))

BEGIN

INSERT INTO @tbl VALUES (@ID, @name)

RETURN

END

/// <summary>

/// 调用表值用户自定义函数

/// </summary>

void Call_HelloFunctionTable()

{

NorthwindDataContext ctx = new NorthwindDataContext();

var p = (ctx.HelloFunctionTable(1, "webabcd")).Single();

result.InnerHtml += "ID：" + p.ID;

result.InnerHtml += " ";

result.InnerHtml += "Name：" + p.Name;

result.InnerHtml += " ";

}

运行结果
ID：1
Name：webabcd

不使用数据加载选项

/// <summary>

/// 不使用数据加载选项

/// </summary>

void DataLoadOptions_Original()

{

NorthwindDataContext ctx = new NorthwindDataContext();

var categories = from c in ctx.Categories select c;

foreach (var c in categories)

{

// 每一次迭代都会执行一条SQL语句来返回当前Category的Product

foreach (var p in c.Products)

{

string productName = p.ProductName + " ";

}

//SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description], [t0].[Picture]

//FROM [dbo].[Categories] AS [t0]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//SELECT [t0].[ProductID], [t0].[ProductName], [t0].[SupplierID], [t0].[CategoryID], [t0].[QuantityPerUnit], [t0].[UnitPrice], [t0].[UnitsInStock], [t0].[UnitsOnOrder], [t0].[ReorderLevel], [t0].[Discontinued]

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [1]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [2]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [3]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [4]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [5]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [6]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [7]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//FROM [dbo].[Products] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [8]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

使用数据加载选项加载数据

/// <summary>

/// 使用数据加载选项加载数据

/// </summary>

void DataLoadOptions_LoadWith()

{

NorthwindDataContext ctx = new NorthwindDataContext();

System.Data.Linq.DataLoadOptions options = new System.Data.Linq.DataLoadOptions();

// Category以LEFT JOIN的方式关联Product

options.LoadWith<Categories>(c => c.Products);

ctx.LoadOptions = options;

var categories = from c in ctx.Categories select c;

foreach (var c in categories)

{

foreach (var p in c.Products)

{

string productName = p.ProductName + " ";

}

//SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description], [t0].[Picture], [t1].[ProductID], [t1].[ProductName], [t1].[SupplierID], [t1].[CategoryID] AS [CategoryID2], [t1].[QuantityPerUnit], [t1].[UnitPrice], [t1].[UnitsInStock], [t1].[UnitsOnOrder], [t1].[ReorderLevel], [t1].[Discontinued], (

// SELECT COUNT(*)

// FROM [dbo].[Products] AS [t2]

// WHERE [t2].[CategoryID] = [t0].[CategoryID]

// ) AS [count]

//FROM [dbo].[Categories] AS [t0]

//LEFT OUTER JOIN [dbo].[Products] AS [t1] ON [t1].[CategoryID] = [t0].[CategoryID]

//ORDER BY [t0].[CategoryID], [t1].[ProductID]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

使用数据加载选项加载数据，并且限制所要加载的数据

/// <summary>

/// 使用数据加载选项加载数据，并且限制所要加载的数据

/// </summary>

void DataLoadOptions_AssociateWith()

{

NorthwindDataContext ctx = new NorthwindDataContext();

System.Data.Linq.DataLoadOptions options = new System.Data.Linq.DataLoadOptions();

// Category以LEFT JOIN的方式关联Product

options.LoadWith<Categories>(c => c.Products);

// 限制所关联的Product

options.AssociateWith<Categories>(c => c.Products.Where(p => p.UnitPrice > 20));

ctx.LoadOptions = options;

var categories = from c in ctx.Categories select c;

foreach (var c in categories)

{

foreach (var p in c.Products)

{

string productName = p.ProductName + " ";

}

// SELECT COUNT(*)

// FROM [dbo].[Products] AS [t2]

// WHERE ([t2].[UnitPrice] > @p0) AND ([t2].[CategoryID] = [t0].[CategoryID])

// ) AS [count]

//FROM [dbo].[Categories] AS [t0]

//LEFT OUTER JOIN [dbo].[Products] AS [t1] ON ([t1].[UnitPrice] > @p0) AND ([t1].[CategoryID] = [t0].[CategoryID])

//ORDER BY [t0].[CategoryID], [t1].[ProductID]

//-- @p0: Input Currency (Size = 0; Prec = 19; Scale = 4) [20]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

相关信息的获取

/// <summary>

/// 相关信息的获取

/// </summary>

void GetInfo()

{

NorthwindDataContext ctx = new NorthwindDataContext();

var categories = from c in ctx.Categories select c;

result.InnerHtml += "ProviderType：" + ctx.Mapping.ProviderType.ToString() + " ";

result.InnerHtml += "DatabaseName：" + ctx.Mapping.DatabaseName + " ";

result.InnerHtml += "ContextType：" + ctx.Mapping.ContextType.ToString() + " ";

result.InnerHtml += "TableName：" + ctx.Mapping.GetTable(typeof(Categories)).TableName + " ";

result.InnerHtml += "Expression：" + categories.Expression.ToString() + " ";

result.InnerHtml += "T-SQL：" + categories.Provider.ToString() + " ";

}

运行结果
ProviderType：System.Data.Linq.SqlClient.SqlProvider
DatabaseName：C:\DOCUMENTS AND SETTINGS\WANGLEI\桌面\VS2008\WEB\APP_DATA\NORTHWIND.MDF
ContextType：DAL.NorthwindDataContext
TableName：dbo.Categories
Expression：Table(Categories).Select(c => c)
T-SQL：SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description] FROM [dbo].[Categories] AS [t0]

字段的延迟加载

/// <summary>

/// 字段的延迟加载

/// </summary>

void DelayLoaded()

{

// 在对象关系设计器（Object Relational Designer）中设置Categories实体的Picture属性的Delay Loaded为True

NorthwindDataContext ctx = new NorthwindDataContext();

var category = (from c in ctx.Categories

select c).Single(c => c.CategoryID == 1);

System.Data.Linq.Binary b = category.Picture;

}

//SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description]

//FROM [dbo].[Categories] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [1]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

//SELECT [t0].[Picture]

//FROM [dbo].[Categories] AS [t0]

//WHERE [t0].[CategoryID] = @p0

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [1]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

在不同的DataContext之间做更新

/// <summary>

/// 在不同的DataContext之间做更新

/// </summary>

void IsVersion()

{

// 在Categories实体的主键上添加属性IsVersion=true，即Time Stamp为True

Categories c = null;

using (NorthwindDataContext ctx = new NorthwindDataContext())

{

ctx.DeferredLoadingEnabled = false;

c = ctx.Categories.First();

c.Description = "webabcd";

}

using (NorthwindDataContext ctx = new NorthwindDataContext())

{

ctx.Categories.Attach(c, true);

ctx.SubmitChanges();

}

//UPDATE [dbo].[Categories]

//SET [CategoryName] = @p2, [Description] = @p3

//WHERE ([CategoryID] = @p0) AND ([CategoryID] = @p1)

//-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [1]

//-- @p1: Input Int32 (Size = 0; Prec = 0; Scale = 0) [1]

//-- @p2: Input String (Size = 9; Prec = 0; Scale = 0) [Beverages]

//-- @p3: Input String (Size = 7; Prec = 0; Scale = 0) [webabcd]

//-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

缓存

/// <summary>

/// 缓存

/// </summary>

void ShowCache()

{

// 查询后数据会被缓存，如果之后以主键查询的话，会先在缓存里查找

NorthwindDataContext ctx = new NorthwindDataContext();

Categories category = ctx.Categories.Single(c => c.CategoryName == "Beverages");

Categories category2 = ctx.Categories.Single(c => c.CategoryName == "Beverages");

Categories category3 = ctx.Categories.Single(c => c.CategoryID == 1);

Categories category4 = ctx.Categories.Single(c => c.CategoryID == 1);

Categories category5 = ctx.Categories.Single(c => c.CategoryID == 2);

Categories category6 = ctx.Categories.Single(c => c.CategoryID == 2);

}

SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description]

FROM [dbo].[Categories] AS [t0]

WHERE [t0].[CategoryName] = @p0

-- @p0: Input String (Size = 9; Prec = 0; Scale = 0) [Beverages]

-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description]

FROM [dbo].[Categories] AS [t0]

WHERE [t0].[CategoryName] = @p0

-- @p0: Input String (Size = 9; Prec = 0; Scale = 0) [Beverages]

-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

SELECT [t0].[CategoryID], [t0].[CategoryName], [t0].[Description]

FROM [dbo].[Categories] AS [t0]

WHERE [t0].[CategoryID] = @p0

-- @p0: Input Int32 (Size = 0; Prec = 0; Scale = 0) [2]

-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.20706.1

OK
[源码下载]

posted @ 2007-10-25 09:14 webabcd 阅读(7447) 评论(16) 编辑收藏举报

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步步为营VS 2008 + .NET 3.5(13) - DLINQ(LINQ to SQL)之用户自定义函数、在不同的DataContext之间做更新、缓存、获取信息、数据加载选项和延迟加载

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