CODEWITHSUNDEEP
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Yvonnila
Yvonnila

Reputation: 646

Get a list of all values in a column of a DataTable in the correct type

I have a DataTable which I populate using a SqlDataAdapter like this: 

Dim dt = New DataTable("Students")
Dim cmd = New SqlCommand("SELECT [Id] ,[Name] FROM [Students]", myADO_SqlConnection)
Dim da = New SqlDataAdapter With {.SelectCommand = cmd}
da.Fill(dt)

In my database, Id is of type Int.

I want to get a list of the values in the Id column. For this I write:

Dim Ids = dt.AsEnumerable.Select(Function(r) r.Item("Id")).ToList

The problem is, that this gives me a List(Of Object). Is there a way that I directly get a List(Of Integer) without casting?

Upvotes: 1

Views: 1045

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460288

You can use the DataRow extension method Field:

Dim Ids = dt.AsEnumerable.Select(Function(r) r.Field(Of Int32)("Id")).ToList()

This method also supports nullable types, so if a column can be null you can write:

Dim nullableColumnList As List(Of Int32?) = dt.AsEnumerable().
    Select(Function(r) r.Field(Of Int32?)("NullableColumnName")).
    ToList()

Upvotes: 3

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