Hype and LINQ

Tired of querying in antiquated SQL?”

I blinked in astonishment when I saw this headline on the LinqPad site. Warming to its theme, the site suggests that what we need is to “kiss goodbye to SSMS“, and instead use LINQ, a modern query language! Elsewhere, there is an article entitled “Why LINQ beats SQL”.

The designers of LINQ, along with many DBAs, would, I’m sure, cringe with embarrassment at the suggestion that LINQ and SQL are, in any sense, competitive ways of doing the same thing. In fact what LINQ really is, at last, is an efficient, declarative language for C# and VB programmers to access or manipulate data in objects, local data stores, ORMs, web services, data repositories, and, yes, even relational databases.

The fact is that LINQ is essentially declarative programming in a .NET language, and so in many ways encourages developers into a “SQL-like” mindset, even though they are not directly writing SQL. In place of imperative logic and loops, it uses various expressions, operators and declarative logic to build up an “expression tree” describing only what data is required, not the operations to be performed to get it. This expression tree is then parsed by the language compiler, and the result, when used against a relational database, is a SQL string that, while perhaps not always perfect, is often correctly parameterized and certainly no less “optimal” than what is achieved when a developer applies blunt, imperative logic to the SQL language.

From a developer standpoint, it is a mistake to consider LINQ simply as a substitute means of querying SQL Server. The strength of LINQ is that that can be used to access any data source, for which a LINQ provider exists. Microsoft supplies built-in providers to access not just SQL Server, but also XML documents, .NET objects, ADO.NET datasets, and Entity Framework elements. LINQ-to-Objects is particularly interesting in that it allows a declarative means to access and manipulate arrays, collections and so on. Furthermore, as Michael Sorens points out in his excellent article on LINQ, there a whole host of third-party LINQ providers, that offers a simple way to get at data in Excel, Google, Flickr and much more, without having to learn a new interface or language.

Of course, the need to be generic enough to deal with a range of data sources, from something as mundane as a text file to as esoteric as a relational database, means that LINQ is a compromise and so has inherent limitations. However, it is a powerful and beautifully compact language and one that, at least in its “query syntax” guise, is accessible to developers and DBAs alike. Perhaps there is still hope that LINQ can fulfill Phil Factor’s lobster-induced fantasy of a language that will allow us to “treat all data objects, whether Word files, Excel files, XML, relational databases, text files, HTML files, registry files, LDAPs, Outlook and so on, in the same logical way, as linked databases, and extract the metadata, create the entities and relationships in the same way, and use the same SQL syntax to interrogate, create, read, write and update them.”