但是在一些情况下可以大大降低你的代码恶心程度，你试试用原生方法写写join，group by，left join？题主问的问题太宽泛，我只能用我的理解简单说一下，还希望题主把具体的上下文说一下吧，我怎么想只能想到linq 2 sql过时了可以说得过去，但也值得学啊，过渡到ef几乎是无痛的也许是你的老师过时了。。。当下linq很火呀
Join 和 GroupJoin 将两个输入序列网格化为一个输出序列。 Join 发出平坦的输出; GroupJoin 发出分层输出。 Join 和 GroupJoin 提供了 Select 和 SelectMany 的替代策略。 Join 和 GroupJoin 的优点是它们在本地内存集合上高效执行,因为它们首先将内部序列加载到键控查找中,避免了重复枚举每个内部元素的需要。缺点是...
Method-Based Query Syntax Examples: Join Operatorshttps://docs.microsoft.com/en-us/dotnet/framework/data/adonet/ef/language-reference/method-based-query-syntax-examples-join-operators** **Perform left outer joinshttps://docs.microsoft.com/en-us/dotnet/csharp/linq/perform-left-outer-joins** **P...
the LINQ declarative query syntax. The C# compiler translates query syntax into method calls. These method calls implement the standard query operators, and have names such asWhere,Select,GroupBy,Join,Max, andAverage. You can call them directly by using method syntax instead of query syntax. ...
the LINQ declarative query syntax. The C# compiler translates query syntax into method calls. These method calls implement the standard query operators, and have names such asWhere,Select,GroupBy,Join,Max, andAverage. You can call them directly by using method syntax instead of query syntax. ...
The C# compiler translates query syntax into method calls. These method calls implement the standard query operators, and have names such as Where, Select, GroupBy, Join, Max, and Average. You can call them directly by using method syntax instead of query syntax. Query syntax and method ...
Using the CreateQuery method: C# 复制 var query1 = from c in context.CreateQuery<Contact>() select c; join The join clause represents an inner join. You use the clause to work with two or more tables that can be joined with a common column value. Example: C# 复制 from ...
When it does come time for you to merge results from different tables, LINQ again provides a SQL-like syntax for joining the tables. Actually, it provides two variations, paralleling the syntax variations supported by different SQL vendors. The first syntax uses the Join keyword to specify a ...
SelectMany,join,GroupJoin后面跟着outer range variable 对于包含单个操作符的,用fluent syntax就比较简洁。最后,有很多操作符是没有对应的query syntax,这就需要使用fluent syntax,至少部分使用。 延迟执行 只有在被枚举的时候才被执行,除了下面的情况: 返回标量或者单个元素的操作符,比如First,Count 转换操作,如To...
They are a convenient way to represent the delegate passed to LINQ queries like System.Func<T, TResult> when the Enumerable.Where method is called as part of narrowing down a result set. Lambda expressions are functions with a different syntax that enables them to be used in an expression ...