Language Integrated Query (LINQ) is a cool feature of .NET languages like C# that allows you to perform SQL-like query right within the language against language’s data structures (lists, arrays etc.) But one drawback of LINQ – you have to know in advance, at compile time which fields to select, what filter conditions would be. […]
LINQ allows to perform various queries against different data structures. Wouldn’t it be great if you could easily export result of a LINQ query to CSV? Fortunately you can! This article by Scott Hanselman explain how and culminates in cool in its simplicity code:
If you’re trying to retrieve distinct rows from your ADO.NET data table using code like or You may find that rows that are being return are not unique. That’s because by default LINQ compares table rows by reference. If you need to compare by actual values – use DataRowComparer in Distinct method call:
Last time I described how LINQ can be used to custom filter ADO.NET DataTable. This time I will demonstrate how this technique can replace built-in server-side filtering in Infragistics UltraWebGrid. By default if server-side filtering is enabled in UltraWebGrid controls, it displays a small “funnel” icon in the column header, if you click this icon […]
ADO.NET DataTable offers handy RowFilter property (via its DefaultView object), for example to filter by some string value and display filtered data in a grid a code like this is used: where odtMyData is a DataTable object and odgDataGrid is a Data Grid. This works well, but what if you need preprocess data in the […]
Linq2Sql has a great use of stored procedures – it converts them into methods which you can easily call using standardized .NET syntax. For example if you have SP: after dragging it into Linq2Sql designer you can call it in your .NET code like this: but there are 2 caveats.
In the past I described how to perform string aggregates in T-SQL. In this post I will show how strings can be concatenated in LINQ. I am using ADO.NET data table as a source for the query, but LINQ being LINQ can pull data pretty much from anything so this example can easily be adjusted. […]
Often you have to operate with flattened data that in reality contains multiple levels of hierarchy. For example it can come as a result of several SQL JOIN statement and look like this: In this example data consist of static root column, region, site, type and state. And the data has clearly defined hierarchy (e.g. […]
LINQ is truly integrated into VB.NET. This allows not only to use LINQ-specific query language in a standard VB.NET code, but use VB.NET code in a LINQ query. Consider function from the previous post. To make it universal we can pass one more parameter “Aggregate Type” and based on that parameter return Min, Max, Avg, […]
I’ve described before how to group and aggregate data in ADO.NET data table using standard .NET 2.0 features. But if you happen to use .NET 3.5 or above and Visual Studio 2008 or above – that entire block of code can be replaced with a single LINQ query: The query at line 3 is a […]