): Returns multiple datasets under a single database operation;• Developers can use strongly typed objects or dynamic objects;• Customize the Entity factory (custom entityfactory) for complex objects that require special handling at the time of creation;• Ability to add additional database support.Fluentdata requires. NET 4.0 and supports SQL Server, sqlazure, SQL Server Compact, and Oracle and MySQL using. NET drivers. For further information, such as code samples and free downloads, please vis
LINQ: getting started with LINQ (1)-Introduction to LINQ query and linq QueryGetting started with LINQ (1)-Introduction to LINQ Query
A query is an expression used to retrieve data from a data source. Over time, people have develo
LINQ: start to use LINQ (2)-Basic LINQ query operations, linq QueryGetting started with LINQ (2)-Basic LINQ query operations
The first step is to specify the data source. Like in most programming languages, variables must be decla
, LINQ to datasets, LINQ to SQL, LINQ to entities, and LINQ to XML.
A. Net Language Integrated Query Based on relational data. It is used to manage relational data in the form of objects and provides rich query functions. It is built on the integration of SQL-Based Schema definitions in public language systems. When
LINQ: start to use LINQ (3)-use LINQ for data conversion, and use linq for Data ConversionGetting started with LINQ (3)-using LINQ for Data Conversion
Language integration query (LINQ)
LINQ is a new thing, but from many articles and discussions, this concept is a bit chaotic. Therefore, we often see the following:
Only data tables and object attributes can be matched one by one in LINQ ......
LINQ Development Guide: map database fields in LINQ ......
In fact, the above two statements refer to the
LINQ is a new thing, but from many articles and discussions, the concept is a bit confusing. So we can often see this:
LINQ can only match data tables to entity attribute one by one ...
LINQ Development Guide: Database field mapping in LINQ ...
In fact, the above two sentences are all
= q.todictionary (p = p.productid);foreach(intKeyinchQdictionary.keys) {Console. WriteLine (key);}Statement Description: This sample uses todictionary to directly evaluate the query and key expression direct key expressions as dictionaryAdo. NET and LINQ to SQLLINQ to SQL is based on the services provided by the ADO provider model. As a result, we were able to mix LINQ to SQL code with existing ADO-out app
Linq learning summary 1-refer to the detailed description of Linq technology, 1-linqKey points:1. The set of linq operations must implement the IEnumerable interface. Therefore, before 3.0, the set that implements this interface must be converted to a Linq-enabled set through the Cast or TypeOf method;
2. the query exp
System.Core.dll, the LINQ to DataSet adds a number of dataset-specific extensions that make it easier to query a set of DataRow objects. These DataSet extensions include operators for comparing row sequences and methods for accessing the column values of a DataRow.2. LINQ to SQLLINQ to SQL is suitable for development that does not require mapping to a conceptual model, and by using
Linq learning summary 1-refer to the detailed description of Linq technology, 1-linq
Two key points:
1. The set of linq operations must implement the IEnumerable interface. Therefore, before 3.0, the set that implements this interface must be converted to a Linq-enabled set
A more concise version will be published in the blog Hall (excluding the English version). I hope this article will help you!
Allowed to reprint, trouble to indicate the source: http://www.cnblogs.com/hanxianlongOriginal article:Http://weblogs.asp.net/scottgu/archive/2007/05/29/linq-to-sql-part-2-defining-our-data-model-classes.aspx
In Part 1 of my LINQ to SQL blog post series I discussed "What Is
LINQ to datasets require the use of System.Core.dll, System.Data.dll and System.Data.DataSetExtensions.dll, add references System.Data and System.Data.DataSetExtensions to the project.1. DataTable Read ListDataSet ds = new DataSet ();//Omit the DS's fill code datatable products = ds. tables["Product"];ienumerableDataSet ds = new DataSet ();//Omit the DS's fill code datatable products = ds. tables["Product"];var rows = products. AsEnumerable () . Se
db.Products where p.UnitsInStock
Statement Description: In this example, the direct key expression of the query and key expression is directly calculated as a Dictionary ADO. NET and LINQ to SQL
LINQ to SQL is based on the services provided by the ADO. NET provider program model. Therefore, we can mix the LINQ to SQL code with the existing ADO. NET applicati
LINQ to objects, LINQ to datasets, LINQ to SQL, LINQ to entities, and LINQ to XML.
A. Net Language Integrated Query Based on relational data. It is used to manage relational data in the form of objects and provides rich query functions. It is built on the integration of S
LinQ query and linq dynamic query
A lot of new content has been added to the project, and LINQ is a very simple but practical content, making it easier for us to operate data. Next, let's give a brief introduction to LINQ.
I. Overview
LinQ (Language-Integrated Query, Langua
LINQ: starts to use LINQ (4)-LINQ to query the type relation of the operation.Start to use LINQ (4)-the type Relationship of the LINQ query operation.
The data source, query itself, and query execution are strongly-typed. The types of variables in the query must be the same
Read the catalogue:
The main design model of 1.LINQ frame
1.1. Chained design mode (System logic is designed in a pipelined way)
1.2. Chained Query method (stepwise processing of each work point in a query expression)
Core design principle of 2.LINQ frame
2.1. Languages above the Managed language (LINQ query expressi
[C1]FROM ( SELECT 1 AS X ) AS [SingleRowTable3]) AS [UnionAll2] ON CAST( [Extent1].[SID] AS bigint) = [UnionAll2].[C1]
Although the operations are troublesome, only one name is found. Relatively speaking, it is better.
Case 3: LINQ to entities does not recognize the method 'int32 get_item (int32 )'
LINQ to entities does not recognize the method 'int32 get_item (int32) 'method, and this method cannot be
get_item (Int32) ' method, and this method cannot is translated into a Store expressionLinq to Entities does not recognize the method "Int64 get_item (Int32)", so the method cannot be converted to a storage expression.And look at the code[CSharp]View Plaincopy
listlong> list = new listlong> {1, 2, 3};
var entity = entityset.where (en = en). SID = = List[1]). ToList ();
In this case, the subscript operation of the array is placed in
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