How to check if the row has data or not in the DataTable?

2016-10-18

Question

_{Tuesday, October 18, 2016 5:15 PM}

Hey,

How to check if the row has data or not in the datatable? for example my rows are : Name / Age. I tried to work with this code:

If Row("Name") or Row("Age") = "" then

else

 AddNewRows()End If

But it didn't work, and it gives me error "Use the new keyword to create an object distance"

Any help?
Greetings,

John.

All replies (13)

_{Tuesday, October 18, 2016 5:20 PM}

A DataTable Rows can be indexed with an Integer and not a String.

Are you maybe meaning to check if the column of a row is empty?

Please post the code that defines and fills the datatable.

Regards Les, Livingston, Scotland

_{Tuesday, October 18, 2016 5:39 PM}

       'dt is DataTable
       For i As Integer = 0 To dt.Rows.Count - 1
            Dim lst As New List(Of Object)(dt.Rows(i).ItemArray)
            Dim valuesarr As String = String.Empty
            For Each s As Object In lst
                valuesarr &= s.ToString
            Next
            If String.IsNullOrEmpty(valuesarr) Then
                MsgBox("Row " & i & " is blank")
            End If
        Next

http://www.codeproject.com/Questions/246050/Remove-empty-rows-from-datatable

Paul ~~~~ Microsoft MVP (Visual Basic)

_{Tuesday, October 18, 2016 6:10 PM}

Hey,

How to check if the row has data or not in the datatable? for example my rows are : Name / Age. I tried to work with this code:
If Row("Name") or Row("Age") = "" then

else

 AddNewRows()End If
But it didn't work, and it gives me error "Use the new keyword to create an object distance"

Any help?
Greetings,

John.

Here is an illustration of a DataGridView with a DataSource as a DataTable. There is a button which fills a list with the indexes of any empty rows and displays a MessageBox of the total. This example is in the form of an example |Project with an empty default Form1.

Option Strict On
Option Infer Off
Option Explicit On
Public Class Form1
    Dim dt As New DataTable()
    Dim DataGridView1 As New DataGridView
    Dim b As New Button
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.Size = New Size(500, 400)
        dt.Columns.AddRange(New DataColumn() _
            {
                New DataColumn("ColA", GetType(Integer)),
                New DataColumn("ColB", GetType(String)),
                New DataColumn("ColC", GetType(String)),
                New DataColumn("ColD", GetType(Double))
            }
        )

        dt.TableName = "MyTable"

        dt.Rows.Add(New Object() {1, "John", "McIntosh", 123.45})
        dt.Rows.Add(New Object() {Nothing, Nothing, Nothing, Nothing})
        dt.Rows.Add(New Object() {2, "Brian", "Jones", 11.3455})
        dt.Rows.Add(New Object() {3, "Andrew", "Jones", 123.45})
        dt.Rows.Add(New Object() {Nothing, Nothing, Nothing, Nothing})
        dt.Rows.Add(New Object() {4, "John", "Smith", 321.1})
        dt.Rows.Add(New Object() {5, "John", "Jones", 321.1})
        dt.Rows.Add(New Object() {Nothing, Nothing, Nothing, Nothing})
        dt.Rows.Add(New Object() {Nothing, Nothing, Nothing, Nothing})
        dt.Rows.Add(New Object() {6, "Mary", "Clark", 11.3455})
        dt.Rows.Add(New Object() {7, "Mary", "Smith", 543.23456})
        dt.Rows.Add(New Object() {8, "Mary", "Duke", 7.89})
        dt.Rows.Add(New Object() {9, "Johny", "McIntosh", 321.1})

        With DataGridView1
            .RowHeadersVisible = False
            .Size = New Size(460, 300)
            .DataSource = dt
        End With
        With b
            .Text = "Check Empty Rows"
            .AutoSize = True
            .BringToFront()
            .Location = New Point(20, DataGridView1.Bottom + 8)
        End With
        Me.Controls.AddRange({DataGridView1, b})
        AddHandler b.Click, AddressOf DGVclick
    End Sub
    Private Sub DGVclick(sender As Object, e As EventArgs)
        Dim lst As New List(Of Integer)
        For r As Integer = 0 To dt.Rows.Count - 1
            Dim s As String = Nothing
            For Each item As Object In dt(r).ItemArray
                s &= item.ToString
            Next
            If s = Nothing Then lst.Add(r)
        Next
        MessageBox.Show("There are " & lst.Count.ToString & " empty rows")
    End Sub
End Class

Regards Les, Livingston, Scotland

_{Wednesday, October 19, 2016 7:05 AM}

Hi John Zack,

The DataRow.IsNull Method (String) gets a value that indicates whether the named column contains a null valus. Hope it will be helpful to you.

Best Regards,

Neda Zhang

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_{Wednesday, October 19, 2016 10:02 AM | 1 vote}

Hello,

What I see in your code is that the check for Name has no condition, you need to place a condition on both Name an age rather than just Age. So a simple fix.

If Row("Name").ToString = "" OrElse Row("Age").ToString = "" Then
    MessageBox.Show("Add new row")
End If

There are several methods (and twist on them) to do this. Here the first checks for row 1 if either column is empty working with strings, second, check a specific row for both fields empty (which is not what you are looking for but wanted to show), last check, do all rows and returns the index of each row meeting the conditions for name and age.

Dim table As New DataTable()
table.Columns.Add("Name", GetType(String))
table.Columns.Add("Age", GetType(String))

table.Rows.Add("Karen", "1")
table.Rows.Add("", "34")
table.Rows.Add("Anne")
table.Rows.Add("Jane", "")
table.Rows.Add("", "")
table.Rows.Add(Nothing, "1")
table.Rows.Add("Anne", "1")

' specific columns are empty
If String.IsNullOrWhiteSpace(table.Rows(1).Field(Of String)("Name")) OrElse String.IsNullOrWhiteSpace(table.Rows(1).Field(Of String)("Age")) Then
    ' add row
End If

' is a specific row totally empty
Dim emptyRow As Object() = {"", ""}
Console.WriteLine(table.Rows(4).ItemArray.SequenceEqual(emptyRow))

' get all rows meeting our condition index
Dim results As List(Of Integer) = table.AsEnumerable _
    .Select(Function(row, index) New With {.Row = row, .Index = index}) _
    .Where(Function(item) String.IsNullOrWhiteSpace(item.Row.Field(Of String)("Name")) OrElse String.IsNullOrWhiteSpace(item.Row.Field(Of String)("Age"))) _
    .Select(Function(item) item.Index) _
    .ToList

If results.Count > 0 Then
    Console.WriteLine(String.Join(",", results))
End If

Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem. Contact via my Twitter (Karen Payne) or Facebook (Karen Payne) via my MSDN profile but will not answer coding question on either.
VB Forums - moderator

_{Wednesday, October 19, 2016 3:18 PM}

You didn't get my point, will make a new thread with more info!

_{Wednesday, October 19, 2016 3:56 PM}

You didn't get my point, will make a new thread with more info!

Please do not start another thread, instead alter the original question to reflect what was missing. If you start a new thread with the same topic myself or another moderator will remove it or merge it with this thread.

_{Wednesday, October 19, 2016 5:11 PM}

Okay, so, i have a program that locks and unlocks folder(s). This program has btnLock and btnUnlock and Text for the path and text for the folder name. When the user press "btnLock" it locks the folder and add rows to the data table. Now, the problem is that the code i use only adds 1 row. I wanna make it as i said before, wanna check if there is data in data table if there is then make a new row with the folder path.text and foldername.text if there isn't then DoNothing..

_{Wednesday, October 19, 2016 5:38 PM}

Okay, so, i have a program that locks and unlocks folder(s). This program has btnLock and btnUnlock and Text for the path and text for the folder name. When the user press "btnLock" it locks the folder and add rows to the data table. Now, the problem is that the code i use only adds 1 row. I wanna make it as i said before, wanna check if there is data in data table if there is then make a new row with the folder path.text and foldername.text if there isn't then DoNothing..

That doesn't make sense.

Maybe you mean when btnlock is selected if the text for a path and text for a folder already exist in a DataTable then don't do anything and if it doesn't already exist then add a row and lock the folder.

And if btnUnlock is selected then remove the row btnUnlock pertains to after unlocking the folder.

La vida loca

_{Wednesday, October 19, 2016 6:19 PM}

Okay, so, i have a program that locks and unlocks folder(s). This program has btnLock and btnUnlock and Text for the path and text for the folder name. When the user press "btnLock" it locks the folder and add rows to the data table. Now, the problem is that the code i use only adds 1 row. I wanna make it as i said before, wanna check if there is data in data table if there is then make a new row with the folder path.text and foldername.text if there isn't then DoNothing..

Well this project sounds familiar. OK, so if I understand your question correctly you want to add a row containing the name of the folder path and the folder name to the DataTable when the folder is locked. Why do you care whether there are any rows currently in the DataTable? Also, if you want to do this you can simply check the Count property of DataTable.Rows to see if it's a value of zero.

Paul ~~~~ Microsoft MVP (Visual Basic)

_{Wednesday, October 19, 2016 6:22 PM}

Well this project sounds familiar...

It does...

"Everybody in this country should learn how to program a computer... because it teaches you how to think." (Steve Jobs)

_{Friday, October 21, 2016 1:45 PM}

Sorry for being late. Was busy. Paul, i care because when i lock the folder it goes to the data table. If i locked another one, it will just replace it, i want it to make another Row. In the same Row"Folder" or Row"Destination another path and name under it.

_{Friday, October 21, 2016 2:47 PM}

Sorry for being late. Was busy. Paul, i care because when i lock the folder it goes to the data table. If i locked another one, it will just replace it, i want it to make another Row. In the same Row"Folder" or Row"Destination another path and name under it.

I think we went through this before in another thread. A new row should not replace a current row unless your code is explicitly doing so, or, if you are removing all the rows from the DataTable and then adding the new row.

If the current row is being removed when a new row is added then you need to look at this section of code to see why, or at least post it so we can see what you are doing.

Paul ~~~~ Microsoft MVP (Visual Basic)

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How to check if the row has data or not in the DataTable?

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