How to Group Data by Multiple Columns Using LINQ?

LINQ uses linq according to multiple groups of group data

In SQL, you can use the group by clause based on multiple columns. This allows you to aggregate data based on the unique combination of the specified column.

LINQ provides a similar grouping mechanism with the Groupby extension method. However, unlike SQL, LINQ processes objects, which requires a way to identify the group standards.

To press multiple columns in Linq, you can use anonymous type to represent the group key. Anonymous type is a temporary and unnamed type that allows you to group the object based on a group of known attributes.

Consider the following SQL query:

To convert this query to linq, you can use anonymous type, as shown below:

<code class="language-sql">SELECT * FROM <table> GROUP BY <column1>, <column2></code>

This code is paid to the rows in the table based on the values ​​of Column1 and Column2. The generated groupdata variables are iGrouping & lt; TKEY, Telement & GT; where TKEY indicates the anonymous type for grouping, and Telement represents the rows in the group.

<code class="language-csharp">var groupedData = table.GroupBy(x => new { x.Column1, x.Column2 });</code>

Then you can iterate these groups and aggregate data as needed, which is similar to the method you do in SQL:

This code will be printed group key (anonymous types with column1 and column2 values) and each line in each group.

<code class="language-csharp">foreach (var group in groupedData)
{
    Console.WriteLine($"Group key: {group.Key}");
    Console.WriteLine("QuantityBreakdown:");

    foreach (var row in group)
    {
        Console.WriteLine($"  - MaterialID: {row.MaterialID}, ProductID: {row.ProductID}, Quantity: {row.Quantity}");
    }
}</code>

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