LINQ
http://www.cnblogs.com/lifepoem/archive/2011/12/16/2288017.html
LINQ is a new feature of .NET Framework 3.5. Its full name is Language Integrated Query, that is, language integrated query, which refers to the combination of query function and language. Thus providing us with a unified way, allowing us to directly query and manipulate various data in C# or VB.NET language.
https://kb.cnblogs.com/zt/linq/
LINQ (Language Integrated Query) Language Integrated Query is a set of extensions for C# and Visual Basic languages. It allows writing C# or Visual Basic code to manipulate in-memory data in the same way as querying a database.