I agree, Mark, odd that it didn't turn up in my searches. However, that question did not provide the answer I needed, unlike this one. I love the fact this question, with an accepted answer not listed in any of the 'duplicates', is still closed as such. Add a comment. Active Oldest Votes. Improve this answer. Darin Dimitrov Darin Dimitrov k gold badges silver badges bronze badges. Yes it provides those features.
For anyone looking to bind in asp. The links in this answer need to be updated. Nick Craver Nick Craver k gold badges silver badges bronze badges. I've seen that one, but I'd rather not pay for it. Adra - There are multiple levels, including a free version but you should really specify "free only" in your question if that's the case, comparatively the Devart stuff is really cheap. If the MySQL ones are of similar quality than this is definitely the direction to go in. I thought I did specify free only by stating 'paid options' as something I didn't like, but I'll try to be more clear in the future.
The following figure shows Belgium selected from the list box and a table with three columns: Name , Population , and CountryCode. In this tutorial you have seen how to create an ASP. Handling Connection Errors. Using GetSchema on a Connection. Using MySqlCommand. Creating and Calling Stored Procedures. Writing a File to the Database. Writing a Custom Authentication Plugin. Fractional Seconds. Problems when Using Invalid Dates. Restricting Invalid Dates. Handling Invalid Dates. Building Custom Listeners.
Creating a Data Source. Creating the Report. Displaying the Report. Asynchronous Methods. Binary and Nonbinary Issues. The MySqlConnection Object.
The MySqlCommand Object. Working with Decoupled Data. Working with Parameters. Working with Stored Procedures. NET Profile Provider.
Tutorial: Web Parts Personalization Provider. Tutorial: Simple Membership Web Provider. Tutorial: Using MySqlScript. Entity Framework 6 Support. Entity Framework Core Support. This avoids duplication, makes results easier to work with, and in most cases it even obviates the need for joining.
For example, suppose we want to retrieve a selection of customers, each with their high-value purchases. In LINQ, you can do this:. HighValuePurchases, here, is a collection. And because we were querying an association property, we didn't need to join. Which means the detail of whether this was a inner or outer join is nicely abstracted away. In this case, the query, when translated to SQL, would be an outer join: LINQ doesn't exclude rows just because a subcollection returns zero elements.
If we wanted something that translated to an inner join, we could do this:. LINQ also supports flat outer joins, adhoc joins, subqueries, and numerous other kinds of queries through a rich set of operators.
What if we wanted to parameterize our previous example, so that the state "WA" came from a variable? This is all we do:. LINQ's parameterization is inline, typesafe, and highly readable. It doesn't just solve the problem—it solves it really well. As because LINQ queries are composable, we can add predicates conditionally. For example, we could write a method as follows:.
If we call this method with null state and minPurchase values, the following SQL is generated when we enumerate the result:. Because our method returns an IQueryable, the query is not actually translated to SQL and run until enumerated. This give the caller a chance to add further predicates, pagination, custom projections, and so on.
In the preceding queries, if we had declared the state variable as an integer rather than a string, the query would fail at compile-time rather than run-time. The same applies if you get any of the table or column names wrong.
This is of real benefit when refactoring: the compiler will tell you if you haven't completely done your job. LINQ lets you effortlessly shift part of the query onto the client for processing. Why would you want to do this? With a heavily burdened database server, it can actually improve performance.
As long as you don't take more data than you need in other words, you still do all the filtering on the server you can often help performance by shifting some of the burden of reordering, transforming and regrouping the results onto a less loaded application server. With LINQ, all you need to do is to slip AsEnumerable into the query, and everything from that point on executes locally.
0コメント