Simplest way how to loop and display through records using textbox, combo box and datetimepicker.
Below is a code but still cant figure it out
Dim dr As DataRow
Dim ds As Dataset
Dim dt As DataTable
<code to fill the dataset>
dt = ds.Tables(0)
For Each dr In dt.Rows
Console.WriteLine (dr("ColName"))
Next
ds.Dispose()
You need two loops to do this - an outer loop for the number of rows in the table, and an inner loop for the columns in each row.
You have the For Each for the rows already, but you need to know how many columns are in the DataRow, and print out the value in each column. You can get the count of columns from the DataTable.
Dim cols As Integer
cols = dt.Columns.Count - 1
For Each dr in dt.Rows
For i As Integer = 0 To cols
Console.WriteLine(dr(i).ToString())
Next
Next
Notice that I call ToString() on the value returned from each column, and reference the column by it's ordinal. When you access a specific column in the DataRow, it returns an Object, so you'll need to cast that value to the correct data type for use in your program.
The code you posted would have only printed the value for the column that had "ColName" as it's column name for each row. If you didn't have a column named "ColName" then you would see an error.
Related
So the boss comes to me and says "I want the value of each agent and the project on one line and the average of all the other agents on the next line so I can easily see if they are above or below average."
the table looks like this:
dt.Columns.Add("AGENT", GetType(String))
dt.Columns.Add("PROJECT", GetType(String))
dt.Columns.Add("Sales", GetType(Integer))
dt.Columns.Add("Declines", GetType(Integer))
dt.Columns.Add("Margin", GetType(Integer))
Ok its all good. One row in the datatable is the agent and project. The next row is the average of all the other agents and project like so:
row 1:
John Smith,
ProjectName,
(other column values)
row 2:
John Smith,
ProjectName & " AVERAGE/TOTAL",
(other column values)
The project name is removed in the SSRS report on the AVERAGE/TOTAL line because of space constraints on the piece of paper it is printed on.
I do the sorting by our standard way of sorting a datatable.
Dim dataView As New DataView(dt1)
dataView.Sort = "AGENT,PROJECT"
dt1 = dataView.ToTable
Return dt1
But now the boss has a new requirement later on. He wants to be able to sort by other columns in the table but keep the two rows the (agent/project and the agent/project AVERAGE/TOTAL) together. So in essence he wants to be able to sort not by one row but the two rows together but the sort value could be "AGENT,Margin". Obviously to keep the two rows together I have to find a way to sort the Project value too.
So I am stumped and would appreciate any thoughts you might have. C# ideas are welcome as well.LINQ is fine but it is going to have to become a datatable.
so you create two tables. One with the row values one one with the average values. Loop through the row values and then do another loop inside that loop to match project names. Its a hack but it worked.
If SortValue = "Default" Then
dt1.Merge(dt)
Dim dataView As New DataView(dt1)
dataView.Sort = "AGENT,PROJECT"
dt1 = dataView.ToTable
Else
Dim dataView As New DataView(dt)
dataView.Sort = SortValue
dt = dataView.ToTable
Dim dtCopy As New DataTable
dtCopy = dt.Clone
For Each row As DataRow In dt.Rows
dtCopy.ImportRow(row)
For i = 0 To dt1.Rows.Count - 1
If dt1.Rows(i).Item("PROJECT").ToString.Replace(" AVERAGE/TOTAL", "") = row.Item("PROJECT") And dt1.Rows(i).Item("AGENT") = row.Item("AGENT") Then
dtCopy.Rows.Add(dt1.Rows(i).Item("AGENT"), dt1.Rows(i).Item("PROJECT"), dt1.Rows(i).Item("SALES"), dt1.Rows(i).Item("Declines"), dt1.Rows(i).Item("Margin"))
End If
Next
Next
dt1 = dtCopy
End If
I am trying to pass a query and existing datatable into a function. The function will query the passed datatable using the passed query and return the result.
Unfortunately, I am unable to return any data. I have posted my code below. Can anyone help me fix it? I don't know what I am doing wrong.
Public Function ExecQueryTest(Query As String, DT As DataTable) As DataTable
Dim Result() As DataRow
'initialize the table to have the same number of columns of the table that is passed into the function
Dim LocalTable As DataTable = DT
'initialize counting variables
Dim x, y As Integer
'use the select command to run a query and store the results in an array
Result = DT.Select(Query)
'remove all items from the localtable after initial formatting
For x = 0 To LocalTable.Rows.Count - 1
LocalTable.Rows.RemoveAt(0)
Next
'for loop to iterate for the amount of rows stored in result
For x = 0 To Result.GetUpperBound(0)
'add each array row into the table
LocalTable.Rows.Add(Result(x))
Next
ExecQueryTest = LocalTable
End Function
If there is a better way to accomplish my goal, I don't mind starting from scratch. I just want to be able to handle dynamic tables, queries, and be able to return the information in a datatable format.
The problem is here:
Dim LocalTable As DataTable = DT
That code does not do what you think it does. DataTable is a reference type, which means assigning DT to the LocalTable variable only assigns a reference to the same object. No new table is created, and nothing is copied. Therefore, this later code also clears out the original table:
'remove all items from the localtable after initial formatting
For x = 0 To LocalTable.Rows.Count - 1
LocalTable.Rows.RemoveAt(0)
Next
Try this instead:
Public Function ExecQueryTest(Query As String, DT As DataTable) As DataTable
ExecQueryTest = New DataTable() 'create new DataTable object to hold results
For Each row As DataRow In DT.Select(Query)
ExecQueryTest.LoadDataRow(row.ItemArray, True)
Next
End Function
Though you may also need to clone each DataRow record.
You can clear a table with just
LocalTable.Clear()
instead of using that cycle, Also the results of your select can be directly converted to datatable using
LocalTable = Result.CopyToDataTable
I have a SQL database with a table "Employees" in it (with large number of rows). By using DataGridView, I want to search for specific "Employee's Name" and change it's "Job". How can I achieve that. I'm using VB.net. Please Help Me.
Not sure if this will help but write a loop that goes through all the values if it finds a match its true if not it is false ,if found the item can be displayed in a textbox and edited
if not a message is displayed saying "no match found"
the editing part can be done using a procedure that will update the value in your grid with what is entered
i can supply code for this if need be but i am unsure if this is what you wish
and there is most likely a better way of doing it
you can loop through your grid, and check if the data you wish to edit exists using the For loop:
Supposing you are using a textbox as the input, and you use a label to hold the employee ID:
Dim EmpIDColumn as Integer = 'array number of your EmpID Column
Dim EmpNameColumn as Integer = 'The array number of the column where your EmpName is
Dim JobColumn as Integer = 'The array number of your job column
For each dr as Datagridviewrow in Datagridview1.Rows
If dr.cells(EmpNameColumn).value = TxtSearchBox.text Then
txtEmpJob.text = dr.cells(JobColumn).value
lblEmpID.Text = dr.cells(EmpIDColumn).value
End if
Next
Okay, so you've searched the record successfully. Next step (after editing the job, and even other details like the name) would be to update the record in the grid. Remember you set the lblEmpID's text to empID in the column? Use it to find the
Record you wish to change in the grid using the same technique above!
Dim EmpIDColumn as Integer = 'array number of your EmpID Column
Dim EmpNameColumn as Integer = 'The array number of the column where your EmpName is
Dim JobColumn as Integer = 'The array number of your job column
For each dr as Datagridviewrow in Datagridview1.Rows
If dr.cells(EmpIDColumn).value = lblEmpID.text Then
dr.cells(JobColumn).value = txtEmpJob.text
dr.cells(EmpNameColumn).value = txtEmpName.text
'then, type in here your SQL Query Update!
End if
Next
I would like to know how can I copy a row in another DataGridView. They are bound with a datatable. I'm trying this but it don't works!
For k As Integer = 0 To gridA.SelectedRows.Count
Dim row As DataRow = dtA.Rows(gridA.SelectedRows(k).Index)
dtB.ImportRow(row)
Next
Then delete rows from gridA:
For k As Integer = 0 To gridA.SelectedRows.Count
dtA.Rows.RemoveAt(gridA.SelectedRows(k).Index)
Next
Using the index of the data grid can be a problem since the rows might be sorted in a different order than the DataTable.
I re-worked your example to use the actual row objects to move and delete:
Dim rows As DataGridViewSelectedRowCollection = gridA.SelectedRows
For Each row As DataGridViewRow In rows
dtB.ImportRow(DirectCast(row.DataBoundItem, DataRowView).Row)
Next
For Each row As DataGridViewRow In rows
dtA.Rows.Remove(DirectCast(row.DataBoundItem, DataRowView).Row)
Next
I have a DataGrid which is bound with a DataTable having two columns which store sequences, in my DataGrid these sequence columns are bound with DataGridViewComboBoxes. User is able to set sequence from ComboBoxes. Default values in sequence columns is 0.
I just want to check duplicacy in both the columns on button click, user should not be able select any duplicate value in both the columns.
If i implement it by using ToTable method of DataView to find distinct values it also takes rows with value "0"
if i implement unique constraint on column on DataTable it also checks for 0.
If try to remove values with 0 it also changes DataGrid As DataGrid is bound with DataTable
If i try to declare a new DataTable from existing dataTable it also gets bound to DataGrid Automatically.
Please help me.
Here is an example of how you can check for duplicate values in a DataTable:
Option Strict On
Module Module1
Sub Main()
Dim dt As New DataTable
dt.Columns.Add("mycolumn", GetType(Integer))
dt.Rows.Add({"1"})
dt.Rows.Add({"2"})
dt.Rows.Add({"2"})
dt.Rows.Add({"4"})
dt.Rows.Add({"7"})
Dim duplicateDictionary As New Dictionary(Of Integer, Integer) 'value, count
For Each row As DataRow In dt.Rows
Dim count As Integer = 0
Dim value As Integer = CInt(row("mycolumn"))
duplicateDictionary.TryGetValue(value, count)
duplicateDictionary(value) = count + 1
Next
For Each kv As KeyValuePair(Of Integer, Integer) In duplicateDictionary
If kv.Value > 1 Then 'we have a duplicate
Debug.WriteLine("{0} is a duplicated value, encountered {1} times", kv.Key, kv.Value)
End If
Next
End Sub
End Module
Adding a UniqueConstraint is possible as well, but I find it too intrusive at times, depending on how your editing works. For direct in-grid editing, you may want the user to save a non-valid record in memory, and allow to fix the error, showing validation errors instead of constraint violation exception. Of course you never save invalid data to the database.