Group by using LINQ

[A_Learner]

Please advise how to group by a data table column name using LINQ. What is the result of it an array of data tables? Please provide a code sample?

[ppr (Peter Preuss)]

@A_Learner

ow to group by a data table column name using LINQ

[HowTo] Overview on different options for grouping data and processing the groups

This HowTo introduces on the different options for grouping data from a datatable in order to process the grouped data. Introduction Grouping data and processing the grouped data is a common scenario e.g. when the grouped data is to aggregate like summing up, find maximum, get the average or concatening items. Lets have a look on following data: [grafik] A possible scenario could be: Create a report containing following information: the region code the sum of CaseCount per RegionCode th…

@A_Learner

What is the result of it

Depending on what is defined in the linq

[HowTo] LINQ (VB.Net) Learning Catalogue

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[N.R_Mane (Narendra Mane)]

which ever you have to group in colmnName write your column name.

From row In dt.AsEnumerable()
Group row By key = row(“ColumnName”) Into Group
Select Group.CopyToDataTable()

1. From row In dt.AsEnumerable(): This part of the LINQ query converts the DataTable dt into an enumerable collection of DataRows.

2. Group row By key = row(“ColumnName”) Into Group: This part groups the rows by the value of the “ColumnName” column. The Group keyword allows us to refer to the group of rows that have the same value in the “ColumnName” column.

3. Select Group.CopyToDataTable(): This part selects each group and converts it into a new DataTable using the CopyToDataTable() method. This method creates a new DataTable from the rows in the group.

in VB.Net

Dim groupQuery = studentList.GroupBy(Function(s) s.Age)
        
For Each ageGroup In groupQuery
            
    Console.WriteLine("Age Group: {0}", ageGroup.Key)  //Each group has a key 
            
    For Each student In ageGroup.AsEnumerable()  //Each group has a inner collection
        Console.WriteLine("Student Name: {0}", student.StudentName)
    Next
Next

Output:
AgeGroup: 18
StudentName: John
StudentName: Bill
AgeGroup: 21
StudentName: Steve
StudentName: Abram
AgeGroup: 20
StudentName: Ram

[A_Learner]

How can this be converted into an array of data tables? Thank you,

[ppr (Peter Preuss)]

as mentioned to you in your other thread

@ppr

Assign Activity:

TableList | List(Of DataTable) =
(From d in dtData.AsEnumerable
Group d by k=d(0).toString.trim into grp=Group
Select t = grp.CopyToDataTable).toList

instead of toList we use toArray

[A_Learner]

Getting an error here, with Groups
Definition of method “Groups” is not accessible in the context.

[ppr (Peter Preuss)]

Typo is corrected.

However we recommend keeping this thread as it is and open a new topic if further assistance is needed

[A_Learner]

Thank you, @ppr
The error is fixed now.