Language-Integrated Query (LINQ) is the name for a set of technologies based on the integration of query capabilities directly into the C# language.
You can write LINQ queries in C# for SQL Server databases, XML documents, ADO.NET Datasets, and any collection of objects that supports IEnumerable or the generic IEnumerable<T> interface.
In Linq-to-SQL if you try to get the first element on a query with no results you will get sequence contains no elements error
ToList returns an empty list
class Program{ public static void Main(){ List<string> list = new List<string> { "a" }; IEnumerable<string> ilist = list.Where(x => x == "ABC").ToList(); System.Console.WriteLine(ilist.Count()); foreach (var item in ilist){ System.Console.WriteLine(item); } Console.ReadLine(); } }
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class Program{ public static void Main(){ List<int> list = new List<int> { 1 }; IEnumerable<int> ilist = list.Where(x => x == 3).ToList(); System.Console.WriteLine(ilist.Count()); foreach (var item in ilist){ System.Console.WriteLine(item); } Console.ReadLine(); } }
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