在VS 2008中使用类型数据集编程模式 [英] Programming pattern using typed datasets in VS 2008

问题描述

我目前正在使用vs2008中的类型数据集：

右键单击app_code添加新数据集，将其命名为tableDS。

打开tableDS，右键单击，添加table adapter

在向导中，选择一个预定义的连接字符串，use SQL语句

select * from tablename和next + next完成。 （我为我的数据库中的每个表生成一个表适配器）

在我的代码中，我只需要一个数据就可以获取一行数据：

cpcDS.tbl_cpcRow tr =（cpcDS.tbl_cpcRow）（new cpcDSTableAdapters.tbl_cpcTableAdapter（））。GetData（）。Select（cpcID =+ cpcID）[0] p>

我相信这将从数据库中获取整个表格，并在dotnet中进行过滤（即不是最佳的），有没有办法让tableadapter文件化结果集在数据库上（IE我想要发送select *从tbl_cpc其中cpcID = 1到数据库）

作为一个附注，我认为这是一个相当好的设计模式，用于从vs2008中的数据库获取数据。它是相当容易的代码，阅读和mantain。但是我想知道有没有更好的其他设计模式呢？我使用数据集进行读取/更新/插入和删除。

解决方案

有一点转变，但是你询问不同的模式 - LINQ怎么样？由于您使用的是VS2008，可能（尽管不能保证）您也可以使用.NET 3.5。

LINQ to SQL数据上下文提供更多的管理访问数据（过滤等）。这是一个选项吗？我不知道现在我会去实体框架（ see here ）。

根据请求编辑

从数据上下文中获取一行，您只需要指定谓词 - 在这种情况下，主键匹配：

  int id = ... //我们要查找
的主键（var ctx = new MydataContext（））{
 SomeType record = ctx.SomeTable.Single（x = > x.SomeColumn == id）; 
 // ... etc 
 
 // ctx.SubmitChanges（）; //提交任何更新
} 
  

使用单一上述是故意的 - 使用[单（谓词）]允许数据上下文充分利用本地内存数据 - 即如果谓词仅在主键列上，则如果数据上下文可能不需要触摸数据库已经看到了这个记录。

然而，LINQ非常灵活;您还可以使用查询语法 - 例如稍微不同（列表）查询：

  var myOrders = from row in ctx.Orders 
其中row.CustomerID = id&&& row.IsActive 
 orderby row.OrderDate 
 select row; 
  

等

I'm currently doing the following to use typed datasets in vs2008:

Right click on "app_code" add new dataset, name it tableDS.

Open tableDS, right click, add "table adapter"

In the wizard, choose a pre defined connection string, "use SQL statements"

select * from tablename and next + next to finish. (I generate one table adapter for each table in my DB)

In my code I do the following to get a row of data when I only need one:

cpcDS.tbl_cpcRow tr = (cpcDS.tbl_cpcRow)(new cpcDSTableAdapters.tbl_cpcTableAdapter()).GetData().Select("cpcID = " + cpcID)[0];

I believe this will get the entire table from the database and to the filtering in dotnet (ie not optimal), is there any way I can get the tableadapter to filer the result set on the database instead (IE what I want to is send select * from tbl_cpc where cpcID = 1 to the database)

And as a side note, I think this is a fairly ok design pattern for getting data from a database in vs2008. It's fairly easy to code with, read and mantain. But I would like to know it there are any other design patterns that is better out there? I use the datasets for read/update/insert and delete.

解决方案

A bit of a shift, but you ask about different patterns - how about LINQ? Since you are using VS2008, it is possible (although not guaranteed) that you might also be able to use .NET 3.5.

A LINQ-to-SQL data-context provides much more managed access to data (filtered, etc). Is this an option? I'm not sure I'd go "Entity Framework" at the moment, though (see here).

Edit per request:

to get a row from the data-context, you simply need to specify the "predicate" - in this case, a primary key match:

int id = ... // the primary key we want to look for
using(var ctx = new MydataContext()) {
   SomeType record = ctx.SomeTable.Single(x => x.SomeColumn == id);
   //... etc

   // ctx.SubmitChanges(); // to commit any updates
}

The use of Single above is deliberate - this particular usage [Single(predicate)] allows the data-context to make full use of local in-memory data - i.e. if the predicate is just on the primary key columns, it might not have to touch the database at all if the data-context has already seen that record.

However, LINQ is very flexible; you can also use "query syntax" - for example, a slightly different (list) query:

    var myOrders = from row in ctx.Orders
                   where row.CustomerID = id && row.IsActive
                   orderby row.OrderDate
                   select row;

etc

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