NOW THAT YOU'VE SEEN several practical examples of LINQ's syntax, it is time to In Visual Studio , attempts to query data in a SQL database from a. LINQ is just another tool for embedding SQL queries into code. □ LINQ is a programming model that introduces queries as a first-class concept into any. Setting up the object mapping □. Setting up the. DataContext Reading data with LINQ to SQL Refining our queries Filtering □.
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The aim of this tutorial is to offer an easy understanding of LINQ to the beginners who are keen to learn the .. Insert, Update, and Delete using LINQ to SQL. LINQ = Language INtegrated Query Brings static type safety to database queries Lack of static type checking in embedded SQL queries. net Pdf This article tells the beginners the basic concepts about connecting to the SQL Server NET Framework and how can you linq to sql tutorial c# pdf.
Example The following example contains five separate queries that show how to query and group files. The returned sequence contains only the elements from the first input sequence that are not in the second input sequence. For accessing the database and also for changing the data in the database, it contains connections string and the functions. The conversion methods in this table whose names start with "As" change the static type of the source collection but do not enumerate it. In LINQ the join clause always works against object collections instead of database tables directly. Some LINQ providers. Calls to query methods can be chained together in one query.
SQL and less like a regular C statement. The method syntax , on the other hand, looks very much like the rest of the C code you have seen in this tutorial.
So, the biggest difference is definitely just the syntax and therefore, you will see both variations used when reading C articles and finding answers to questions you might have. It seems that the query syntax is slightly more popular because some people find it easier to read than the method syntax - these might be people who are used to expressing data retrieval operations in SQL anyway.
On the other hand, if you have never used a query language like SQL before, but you have some C experience, then you might find the method syntax easier to read. Also, for at least a couple of operations, like counting the items in the result of the query, you will have to use the method syntax.
In the method syntax example, you might notice something that you haven't seen before, as a parameter to the Where method. It looks like this:. Therefore you will also see it a lot in the following articles, and while I will go into greater details about Lambda Expressions in another article, this is a good time to get a very basic understanding of how they work.
It's actually quite simple.
On the left side , we have the input parameter s - there can be several, but in our example, there's just one, which is the name variable. In this case, it comes from the Where method, from iterating over our list of names and we get to pick the name. I chose "name", because that's what you'll find in a list of names, but you could also call it "x", "z", "foobar" or anything else.
This is where we generate the expected result - in this case, a boolean value telling the Where method whether to include the name in question or not.
We answer that with an expression, saying that we want to include the name if it has a length of 8 or less characters.
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