I am developing a small program to get the maximum of a specific column in a gridview (DevExpress), but I could not execute it as I wanted.
Can you support me in seeing where I have the error?
Dim cells() As GridCell = GridView2.GetSelectedCells()
Dim values As New List(Of Decimal)()
For i As Integer = 0 To GridView2.RowCount - 1
Dim value As Decimal = Convert.ToDecimal(GridView2.GetRowCellValue(cells(i).RowHandle, cells(i).Column))
values.Add(value)
Next i
values.Sort()
MsgBox(values.Max().ToString())
Regards.
With the built in DataGridView, the number of rows can be Rows.Count -2 because there is an extra row for the user to enter a new record. I have no idea if DevExpress works that way but it is worth a try.
For i As Integer = 0 To GridView2.RowCount - 2
If your GridView uses a DataTable as a DataSource, then the following code might help. If the DataTable is still available then just start with that. Otherwise extract it from the grid.
DataTable does not implement IEnumerable but there is an extension method to get the interface (.AsEnumerable).
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim dt = DirectCast(DataGridView1.DataSource, DataTable)
Dim maxValue = Aggregate r In dt.AsEnumerable
Into MaxID = Max(r("ID")) '"ID" is the name of a column
MessageBox.Show(maxValue.ToString)
End Sub
Same thing for Min just change Max to Min.
Calculate Total Summary for Grid Column
gridView1.Columns("UnitsInStock").Summary.Add(DevExpress.Data.SummaryItemType.Average, "UnitsInStock", "Avg={0:n2}")
gridView1.Columns("UnitsInStock").Summary.Add(DevExpress.Data.SummaryItemType.Sum, "UnitsInStock", "Sum={0}")
Dim item As GridColumnSummaryItem = New GridColumnSummaryItem(DevExpress.Data.SummaryItemType.Max, "UnitsInStock", "Max={0}")
gridView1.Columns("UnitsInStock").Summary.Add(item)
Devexpress Documentation:
https://documentation.devexpress.com/WindowsForms/DevExpress.XtraGrid.Columns.GridColumn.Summary.property
https://documentation.devexpress.com/WindowsForms/9677/Controls-and-Libraries/Data-Grid/Examples/Summaries/How-to-Calculate-Single-Total-Summary-for-Grid-s-Column
Related
I have some code that is intended to:
1. Loop through a datagrid that is user populated
2. Search an access database using the input criteria
3. Return the results as a datatable
4. Merge additional results to that datatable
5. Bind the merged table results to a DataGridView
The query works, results return as expected with a single value search. The query will also return one of the two test values if I use the user input DataGridView. However, it will not combine the two results before outputting to the results_DataGridView. I have also tried using .Fill from the adapter to add onto my temp table and use that as the datasource.
Option Strict On
Dim dt_TempTable As New DataTable
Dim dt_ContentsTable As New DataTable
Dim SerialNumbers As New List(Of String)
Dim PanelIDs As New List(Of String)
Dim MultiSearch As Boolean
Private Sub bgwk_data_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles bgwk_data.DoWork
If Not (MultiSearch) Then
Retrieveinfo(Me.txt_SerialNumber.Text, Me.txt_PanelID.Text) 'Local
Else
Dim arrSN As String() = SerialNumbers.ToArray()
Dim arrPID As String() = PanelIDs.ToArray()
For i = 0 To arrSN.Count - 1
If i > 0 Then
Retrieveinfo(arrSN(i), arrPID(i)) 'Local - Run query and create a new temp table of results
dt_ContentsTable.Merge(dt_TempTable) 'Merge new temp table to current contents table
Else
dt_ContentsTable = Retrieveinfo(arrSN(i), arrPID(i)) 'Return the original temp table to the contents table (datagridview datasource)
End If
Next
End If
End Sub
'Gets the Data by SerialNumber and saves it to dt_TempTable to be bound afterwards
Private Function Retrieveinfo(SerialNumber As String, PanelID As String) As DataTable
Dim ds As New datasource
Dim tblAdapt As New datasourceTableAdapters.toHTML_SPC_DataTableAdapter
tblAdapt.GetData(dt_TempTable, SerialNumber, PanelID)
Return dt_TempTable 'Return the table
End Function
'Updates dg_data with the datatable from Retrieveinfo and refreshes the form
Private Sub bgwk_dataRunWorkerCompleted(sender As Object, e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bgwk_data.RunWorkerCompleted
'Unlocks ability to search new things
Me.txt_PanelID.ReadOnly = False
Me.txt_SerialNumber.ReadOnly = False
Me.dg_data.ReadOnly = False
'Binds the backgroundworker results to the datagridview
Me.dg_data.DataSource = Nothing
Me.dg_data.DataSource = dt_ContentsTable
Me.dg_data.Refresh()
Me.Refresh()
End Sub
I understand that merge can be used on DataTables, but perhaps this is incorrect usage?
I'd go with a condition in the multi-search loop:
If dt_ContentsTable.Rows.Count = 0 Then
dt_ContentsTable = dt_TempTable.Clone()
End If
dt_ContentsTable.Merge(dt_TempTable)
This way, the first time, its at least creating the columns of the dt_ContentsTable.
I also don't see any code in the single search where dt_ContentsTable is assigned. So, in the single search, I recommend you assign dt_ContentsTable to dt_TempTable.
The text file contains lines with the year followed by population like:
2016, 322690000
2015, 320220000
etc.
I separated the lines substrings to get all the years in a list box, and all the population amounts in a separate listbox, using the following code:
Dim strYearPop As String
Dim intYear As Integer
Dim intPop As Integer
strYearPop = popFile.ReadLine()
intYear = CInt(strYearPop.Substring(0, 4))
intPop = CInt(strYearPop.Substring(5))
lstYear.Items.Add(intYear)
lstPop.Items.Add(intPop)
Now I want to add the population amounts together, using the .Items to act as an array.
Dim intPop1 As Integer
intPop1 = lstPop.Items(0) + lstPop.Items(1)
But I get an error on lstPop.Items(1) and any item other than lstPop.Items(0), due to out of range. I understand the concept of out of range, but I thought that I create an index of several items (about 117 lines in the file, so the items indices should go up to 116) when I populated the list box.
How do i populate the list box in a way that creates an index of list box items (similar to an array)?
[I will treat this as an XY problem - please consider reading that after reading this answer.]
What you are missing is the separation of the data from the presentation of the data.
It is not a good idea to use controls to store data: they are meant to show the underlying data.
You could use two arrays for the data, one for the year and one for the population count, or you could use a Class which has properties of the year and the count. The latter is more sensible, as it ties the year and count together in one entity. You can then have a List of that Class to make a collection of the data, like this:
Option Infer On
Option Strict On
Imports System.IO
Public Class Form1
Public Class PopulationDatum
Property Year As Integer
Property Count As Integer
End Class
Function GetData(srcFile As String) As List(Of PopulationDatum)
Dim data As New List(Of PopulationDatum)
Using sr As New StreamReader(srcFile)
While Not sr.EndOfStream
Dim thisLine = sr.ReadLine
Dim parts = thisLine.Split(","c)
If parts.Count = 2 Then
data.Add(New PopulationDatum With {.Year = CInt(parts(0).Trim()), .Count = CInt(parts(1).Trim)})
End If
End While
End Using
Return data
End Function
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim srcFile = "C:\temp\PopulationData.txt"
Dim popData = GetData(srcFile)
Dim popTotal = 0
For Each p In popData
lstYear.Items.Add(p.Year)
lstPop.Items.Add(p.Count)
popTotal = popTotal + p.Count
Next
' popTotal now has the value of the sum of the populations
End Sub
End Class
If using a List(Of T) is too much, then just use the idea of separating the data from the user interface. It makes processing the data much simpler.
I have an SQL query that returns 2 columns of values:
country | number
NA | 1
IN | 2
CN | 3
DE | 4
And so on.
I am trying to do one of the following:
Assign these values to variables I can copy to an excel workbook
Or just use the DGV as a medium to copy values to text boxes.
For example, I have a form with country labels and textboxes next to them. I would want to click a button and have the data copied to the matching text box.
DGV number value where DGV row value = CN would be 3 and that value would be copied to the CN value text box.
If you are only using the DGV as a medium, but not actually displaying it, use a dictionary instead. Output the SQLDataReader using the SQLcommand(cmd) with the country code being the key and the number being the value. Then its as simple as:
Dim dc As Dictionary(Of String, String) = New Dictionary(Of String, String)
Dim cmd As SqlCommand = "your query string"
cmd.Connection.ConnectionString = "your con string"
Using sqlrdr As SqlDataReader = cmd.ExecuteReader()
While (sqlrdr.Read())
dc.Add(sqlrdr(0), sqlrdr(1))
End While
End Using
Then just output to the textbox:
txtNA.Text = dc.Item("NA")
If the countries are fixed as your question refers, then you could use something like this:
First, use the names of the countries to name the TextBoxes (txtNA, txtIN, txtCN,...)
Then you can put this code:
Try
For i = 0 To DataGridView1.RowCount - 1
Me.Controls("txt" & DataGridView1.Rows(i).Cells(0).Value.ToString).Text = _
DataGridView1.Rows(i).Cells(1).Value.ToString()
Next
Catch
End Try
The following will not work 'as is' if using classes via dragging tables from the data source window in the ide. We would need to cast objects not to a DataTable but to the class definition in a TableAdapter, DataSet and BindingSource.
Here is a method which reads from SQL-Server database table, places data into a DataTable, data table become the data source for a BindingSource which becomes the data source for the DataGridView. Using a BindingSource we now use the BindingSource to access row data rather than the DataGridView and it's always best to go to the data source rather than the user interface.
BindingSource.Current is a DataRowView, drill down to Row property then field language extension method to get strongly typed data for the current row if there is a current row as you will note I am using two forms of assertions, first, do we have a data source and is the data source populated then we see if there is indeed a current row.
From here we can set variable, properties or control text to the field values of the current row.
Note in form load I seek a specific country (totally optional) and then if found go to that row.
Least but not last, I like using xml literals when doing SQL in code so there is no string concatenation and we can format the statement nicely.
Public Class Form1
''' <summary>
''' Permits obtaining row data in DataGridView
''' </summary>
''' <remarks></remarks>
Dim bsCountries As New BindingSource
Public Property Country As String
Public Property CountryNumber As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim dt As New DataTable
Using cn As New SqlClient.SqlConnection With
{
.ConnectionString = My.Settings.KarenDevConnectionString
}
Using cmd As New SqlClient.SqlCommand With {.Connection = cn}
' xml literal to make command text
cmd.CommandText =
<SQL>
SELECT [ID],[Country],[Number]
FROM [Countries]
</SQL>.Value
cn.Open()
dt.Load(cmd.ExecuteReader)
dt.Columns("ID").ColumnMapping = MappingType.Hidden
bsCountries.DataSource = dt
DataGridView1.DataSource = bsCountries
' let's try and move to a country
Dim index As Integer = bsCountries.Find("Country", "CN")
If index > -1 Then
bsCountries.Position = index
End If
End Using
End Using
End Sub
''' <summary>
''' Put field values into TextBoxes
''' </summary>
''' <remarks></remarks>
Private Sub DoWork()
If bsCountries.DataSource IsNot Nothing Then
If bsCountries.Current IsNot Nothing Then
Dim row As DataRow = CType(bsCountries.Current, DataRowView).Row
TextBox1.Text = row.Field(Of String)("Country")
TextBox2.Text = row.Field(Of Integer)("Number").ToString
' we can also do this
Me.Country = row.Field(Of String)("Country")
Me.CountryNumber = row.Field(Of Integer)("Number")
End If
End If
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
DoWork()
End Sub
End Class
I call into a function which runs a query into SQLServer and returns a DataTable with multiple columns. I want the data from the DataTable to change rows according to the selected item in the combobox.
Dim dt As New DataTable
Dim rInt As New Int32
dt = subGetDB()
rInt = ComboBox1.SelectedIndex
Textbox1.Text = dt.Rows(rInt)("description").ToString()
TextBox2.Text = dt.Rows(rInt)("accountFilter").ToString()
Am I on the right track with this so far?
Yes ... but you need to put all of the code above into the SelectedValueChanged event for the ComboBox1 object.
I have a BindingSource bound to a DataTable.
I use the BS Filter and would like to iterate the filtered dataset of the DataTable using the Bindingsource.
I know I can do a MoveFirst and the MoveNext and each time using the BS.Position get the correct row in the underlying DataTable.
But how do I know when the sets ends? I'm sure there must be such a property, but what is it?
Private Sub BindDataGridView()
Dim count As Integer = 0
For count = 0 To EmployeeListBindingSource.Count - 1
Dim RowIndex As Integer = dataGrdView1.Rows.Add()
Dim row As DataRowView = DirectCast(EmployeeListBindingSource.Item(count), DataRowView)
dataGrdView1.Rows(RowIndex).Cells(0).Value = row.Item(1).ToString
dataGrdView1.Rows(RowIndex).Cells(2).Value = row.Item(0).ToString
Next
End Sub
Declare a row as:
Dim row As DataRowView = DirectCast(EmployeeListBindingSource.Item(count), DataRowView)
Then, access columns like:
row.Item(1).ToString
Compare it with if CompareStr <> row.Item(1).ToString then
I hope this helps.
BindingSource has Count property