With LINQ, a query is a first-class language construct, just like classes, methods, and events. When you write queries, the most visible "language-integrated" part of LINQ is the query expression. Query expressions are written in a declarative query syntax. By using query syntax, you ...
LINQDev.Common.Contact.PublishContacts(contacts); 转换Employee对象的ArrayList 为Contact对象数组,我首先将Employee对象的ArrayList使用Cast Standard Query Operator转换成一个IEnumerable<Employee>序列。这是必须的,因为要使用旧的ArrayList集合类。语法上说,ArrayList是存储System.Object 类 类型对象。所以我必须转换Employee...
Pro LINQ: Language Integrated Query in C# 2008 你是否注意到我是如何解析XML数据到对象类型XElement中的?我没有创建XMLDocument。 LINQ 到 XML 的好处是扩展XML API。现在,根据 W 3 C 文档对象模型 (DOM) XML API 需要, 替代了 XmlDocument,LINQ 到 XML 允许开发人员使用XElement 类进行Element级别交互。
When you write queries, the most visible "language-integrated" part of LINQ is the query expression. Query expressions are written in a declarativequery syntax. By using query syntax, you perform filtering, ordering, and grouping operations on data sources with a minimum of code. You use the ...
Customers where (from o in db.Orders where o.ShipCountry == “Germany” select o.CustomerID).Contains(c.CustomerID); This query can't be handled by the current data layer, and while no errors are diagnosed at compile time, an error would occur at run time....
When you write queries, the most visible "language-integrated" part of LINQ is the query expression. Query expressions are written in a declarativequery syntax. By using query syntax, you perform filtering, ordering, and grouping operations on data sources with a minimum of code. You use the ...
In the following example, Customers represents a specific table in the database, and the type of the query result, IQueryable<T>, derives from IEnumerable<T>. C# Copy Northwnd db = new Northwnd(@"c:\northwnd.mdf"); // Query for customers in London. IQueryable<Customer> custQuery = ...
In the following example, Customers represents a specific table in the database, and the type of the query result, IQueryable<T>, derives from IEnumerable<T>. C# Copy Northwnd db = new Northwnd(@"c:\northwnd.mdf"); // Query for customers in London. IQueryable<Customer> custQuery = ...
Northwnd db =newNorthwnd(@"c:\northwnd.mdf");// Query for customers in London.IQueryable<Customer> custQuery =fromcustindb.Customerswherecust.City =="London"selectcust; 有关如何创建特定类型的数据源的详细信息,请参阅各种 LINQ 提供程序的文档。 但基本规则很简单:LINQ 数据源是支持泛型IEnumerable<...
from num in numbers where (num % 2) == 0 select num; // 3. Query execution. foreach (int num in numQuery) { Console.Write("{0,1} ", num); } } } 下图演示完整的查询操作。 在 LINQ 中,查询的执行不同于查询本身。 换句话说,仅通过创建查询变量不会检索到任何数据。