这个示例在Group By子句 后使用Where子句查找所有至少有10种产品的类别。 说明:在翻译成SQL 语句时,在最外层嵌套了Where条件。 10.多列(Multiple Columns) var categories = from p in db.Products group p by new { p.CategoryID, p.SupplierID } into g select new { g.Key, g }; 语句描述:使用Group...
select o).ToList(); 语句描述:查找"AROUT", "BOLID" 和 "FISSA" 这三个客户的订单。先定义了一个数组,在LINQ to SQL中使用Contains,数组中包含了所有的CustomerID,即返回结果中,所有的CustomerID都在这个集合内。也就是in。 你也可以把数组的定义放在LINQ to SQL语句里。比如: var q = ( from o in ...
这个示例在 Group By 子句 后使用 Where 子句查找所有至少有 10 种产品的类别。 说明:在翻译成 SQL 语句时,在最外层嵌套了 Where 条件。 10.多列(Multiple Columns) var categories = from p in db.Products group p by new { p.CategoryID, p.SupplierID } into g select new { g.Key, g }; 语句...
Add months to GETDATE() function in sql server Add new row to datagridview one by one dynamically Add Node existing XML file Add one Column runtime to datagrid view at specific index in C# Add picture into specified Excel cell Add registry values in setup project ADD Root Node to XML in...
LINQ to SQL applications are easy to get started. Objects linked to relational data can be defined just like normal objects, only decorated with attributes to identify how properties correspond to columns. Of course, it is not even necessary to do this by hand. A design-time tool is provid...
projection since it uses 'Distinct' or 'Group By' operations and doesn't project key columns of all of it's tables which are required to generate results on client side. Missing column: t.ID. Either add column(s) to the projection or rewrite query to not use 'GroupBy'/'Distinct' ...
A function to extract the key for each element. resultSelector Type: System.Linq.Expressions.Expression<Func<TKey, IEnumerable<TSource>, TResult>> A function to create a result value from each group. Return Value Type: System.Linq.IQueryable<TResult> An T:System.Linq.IQueryabl...
The Max<TSource>(IEnumerable<TSource>, Func<TSource, Int32>) method uses the Int32 implementation of IComparable<T> to compare values. You can apply this method to a sequence of arbitrary values if you provide a function, selector, that projects the members of source into...
LINQ to SQL: SQL Integration LINQ to XML: XML Integration Summary .NET Language-Integrated Query After two decades, the industry has reached a stable point in the evolution of object-oriented (OO) programming technologies. Programmers now take for granted features like classes, objects, and method...
A projection function to apply to each element of the input sequence. resultSelector Type: System.Linq.Expressions.Expression<Func<TSource, TCollection, TResult>> A projection function to apply to each element of each intermediate sequence. Return Value Type: System.Linq.IQueryable<T...