programming notes…
Jul
27
2009
This structure keeps coming up :
dsSchools = mydata 'Create table to bind to dataGrid Dim dt As New DataTable Dim nameCol, activeCol As New DataColumn dt.Columns.Add(nameCol) dt.Columns.Add(activeCol) Dim dRow As DataRow = dt.NewRow For Each dr As DataRow In dsSchools.Tables(0).Rows If Not dr("title") Is DBNull.Value Then dRow(nameCol) = dr("title") If Not dr("IsActive") Is DBNull.Value Then dRow(activeCol) = dr("isActive").ToString dt.Rows.Add(dRow) Next
Jun
04
2009
I had a datatable that I needed to sort by a certain column. Here is what I did, if you have a better idea, please let me know!
'Set up the variables for the sort: Const Sort_Column_Key As String = "Test Order" 'This is your column name Const Sort_Direction As String = " ASC" Const Sort_Format As String = "{0} {1}" 'Sort the chartData dataTable so we print the data in the right order - This sorts chartData.DefaultView.Sort = String.Format(Sort_Format, Sort_Column_Key, Sort_Direction) 'Now for me to use it in my future FOR EACH loop, I had to create a new table to put the sorted data into... GOT A BETTER WAY? Let me know! Dim chartData2 As DataTable = chartData.DefaultView.ToTable
This worked well for me! I hope it helps someone else! t
Jun
04
2009
You want to add a column to a dataTable:
Dim testColumn As New DataColumn
Now you want to change the dataType (default is a string):
testColumn.DataType = Type.GetType(“System.Int32″)
Ya, nice and simple right… (would it have been too hard just to say ‘= Integer’???
(“System.String”) is the string…beyond that, you tell me.
Feb
11
2009
Here is an example of writing a datatable into a direct Memorystream and then writing that out to a textBox — this can all be done from an .aspx page and does not require a file to be involved.
'CREATE A DATATABLE AND FILL IT WITH SOME DATA
Dim dt As DataTable = New DataTable
Dim dcID As New DataColumn("ID")
Dim dcName As New DataColumn("Name")
dt.Columns.Add(dcID)
dt.Columns.Add(dcName)
Dim row1, row2, row3 As DataRow
row1 = dt.NewRow()
row1.Item("ID") = "1232444"
row1.Item("Name") = "Todd Eric Vance"
dt.Rows.Add(row1)
row2 = dt.NewRow()
row2.Item("ID") = "154656232444"
row2.Item("Name") = "Tod5454d Eric gggVance"
dt.Rows.Add(row2)
row3 = dt.NewRow()
row3.Item("ID") = "1232444"
row3.Item("Name") = "Tgfgfg fggfric Vyttance"
dt.Rows.Add(row3)
'CREATE MEMORYSTREAM AND STREAMWRITER
Dim ms As MemoryStream = New MemoryStream
Dim sw As StreamWriter = New StreamWriter(ms)
'WRITE COLUMN NAMES TO STREAM
Dim iColCount As Integer = dt.Columns.Count
For i As Integer = 0 To iColCount - 1
sw.Write(dt.Columns(i))
If i < iColCount - 1 Then sw.Write(",")
Next
sw.WriteLine()
'WRITE ROWS TO STREAM
For Each dr As DataRow In dt.Rows
For i As Integer = 0 To iColCount - 1
If Not dr(i) Is DBNull.Value Then sw.Write(dr(i).ToString())
If i < iColCount - 1 Then sw.WriteLine()
Next
Next
sw.WriteLine()
sw.Flush()
'OPEN A READER - SET THE MEMORYSTREAM TO THE BEGINNING
'WRITE IT TO A TEXTBOX
Dim sr As New StreamReader(ms)
ms.Seek(0, SeekOrigin.Begin)
Dim mystring As String = sr.ReadToEnd
tb1.Text = mystring
sr.Close()Sep
21
2008
Simple class here – but I needed just some random data in a datatable and I didn’t want to have to type it all in by hand.
I like this simple little class because one could easily change it to take the type and number of columns they need and then fill them randomly (creating random names could be done but was not implemented here– I have an idea at the bottom).
Anyway I create a class that will contain a table :
Public Class RandomDataTable
Public dt As New DataTable(“random”)
Public name As New DataColumn(“Name”, System.Type.GetType(“System.String”))
Public value As New DataColumn(“Value”, GetType(Integer))
Dim rndm As New Random
Dim dr As DataRow
Now we have a datatable that will have two columns. Next I create the constructor to take in the number of needed rows (howManyResults)… as well as a minimum range for the data and a maximum range for the data.
‘Make random data set of 2 items and numbers
Public Sub New(ByVal howManyResults As Integer, ByVal rangeMin As Integer, ByVal rangeMax As Integer)
Now I add the columns, loop through the number of results and fill in the two columns with Entity# and the Random data number ( I used a random object and called its min max function):
dt.Columns.Add(name)
dt.Columns.Add(value)
For i As Integer = 1 To howManyResults
Dim nameString = “Entity ” + i.ToString
Dim rowValue = rndm.Next(rangeMin, rangeMax)
dr = dt.NewRow()
dr.Item(name) = nameString
dr.Item(value) = rowValue
dt.Rows.Add(dr)
Next
And that is it! I create the class like this DIM MyRandomTable as dataTable = new RandomDataTable(50, 2, 100) and I have a nice filled in table of random data that I can then work with!
** ON THE NAME THING — I am right now planning on extending this by making me first names and last names… I plan on making a firstName array of about 5-10 names and a lastName array of 5-10 names and then in my loop – call a random function to grab random firsts and match them with random lasts… should be interesting.
Any thoughts or ideas on how to extend this???? Let me know!
