I have the following code:
Try
Dim queryString As String
queryString = "Insert into ServiceRecords([Personnel]) Values(#Personnels)"
command1 = New OleDbCommand(queryString, connection)
For i As Integer = 0 To Me.ListBox1.Items.Count + 1
command1.Parameters.AddWithValue("Personnels", ListBox1.Items(i))
command1.Parameters.Clear()
command1.ExecuteNonQuery()
Next
Catch ex As Exception
End Try
But I get the error below, and I don't know how to fix it. I think it happens because of my code.
And this is what I get:
Let's review.
First, as muffi suggested, use the Add method instead of .AddWithValue but instead of DBType use OLEDBType. There is not .String type in OleDBType. You will have to check your Access db to get the correct datatype. Probably VarChar. In addition, the parameter name should match the parameter name in your query string. With Access the position is the important thing but with other databases the name matters.
Second, as Charles suggested, change the plus one to minus 1. Most people start counting at one but computers usually start at zero so the upper index of the ListBox is one less than the Count (remember you are starting at zero not one).
Third , as Charles also pointed out it is wrong to clear the parameters before you execute. Then you would have nothing in your parameter. It is not necessary to clear them at all because you are overwriting the Value property with each iteration of your loop and I have set the name and datatype outside the loop because they stay the same. We don't want to reset properties for each iteration when they don't change.
command1.Parameters.Add("#Personnels", OleDbType.VarChar)
For i As Integer = 0 To ListBox1.Count -1
command1.Parameters("#Personnels").Value = ListBox1.Items(i)
command1.ExecuteNonQuery
Next
Related
I am searching a database and pulling results from it. Before displaying it in WPF I am checking the contents of the text in a field called PrimarySponsor which can be (1) blank/null (2) number at 3rd character (3) persons name. I am currently using Char.IsNumber to check option 2 if there is a number at position 4.
If reader("PrimarySponsor") Is DBNull.Value Then
resultxPrimSpon = ""
ElseIf Char.IsNumber(reader("PrimarySponsor"), 3) Then
resultxPrimSpon = "Terminated"
Else
resultxPrimSpon = reader("PrimarySponsor")
End If
Before I put the Char.IsNumber check in I was getting 4 results displaying. When i add the Char.IsNumber code I only get 2 results along with the error;
Error while connecting to SQLServer.Sepcified argument was out of the range of valid values. Parameter name: index.
Anyone have any ideas about why this is happening or how to work around it?
It's not clear where you get that error because Char.IsNumber is not a sql-server method. So i assume that it's a custom message from you. However, the "Specified argument was out of the range" is documented:
ArgumentOutOfRangeException: index is less than zero or greater than
the last position in s.
So it seems that at least one of the strings is shorter than 4 characters. In general you should store the reader values in a variable of the correct type if you have to access it more than once. In this case in a String-variable.
But it's also a good idea to create a custom type that has all properties. Then you can add all to a List(Of T). Here's an example:
Public Class Sponsor
Public Property PrimarySponsor As String
End Class
Of course you could also fill a List(Of String) instead of a List(Of Sponsor). Then you don't need to create a new type. But i assume that you have more than one column in the table. Using a custom type increases readability and maintainability much.
....
Dim allSponsors As New List(Of Sponsor)
Using reader = command.ExecuteReader()
If reader.HasRows Then
Dim primSponsorColumnIndex = reader.GetOrdinal("PrimarySponsor")
While reader.Read
Dim sponsor As New Sponsor()
If reader.IsDBNull(primSponsorColumnIndex) Then
sponsor.PrimarySponsor = ""
Else
sponsor.PrimarySponsor = reader.GetString(primSponsorColumnIndex)
If sponsor.PrimarySponsor.Length >= 4 AndAlso _
Char.IsDigit(sponsor.PrimarySponsor(3)) Then
sponsor.PrimarySponsor = "Terminated"
End If
End If
allSponsors.Add(sponsor)
End While
End If
End Using
First use DataReader.IsDBNull to check if the value is Null. Then check if Length >= 4 before you use Char.IsDigit(sponsor.PrimarySponsor(3)) to avoid the ArgumentOutOfRangeException.
Difference between Char.IsDigit() and Char.IsNumber() in C#
I am running an SQL Query with data readers in vb.net
reader3 = myCommand3.ExecuteReader
reader3.Read()
If reader3.HasRows Then
FromToDates = reader3.GetString(3)
End If
There are no rows being returned in this particular query, however even though the if reader3.HasRows is being used its still showing an error saying:
Additional information: Data is Null. This method or property cannot be called on Null values.
this is when trying to set the FromToDates variable but there are no rows being returned so it should not even reach this part
I doubt that there are no rows, i assume that there is at least one row where the value is NULL. You could check it with the IsDBNull-method:
If reader3.HasRows AndAlso Not reader3.IsDbNull(3) Then
FromToDates = reader3.GetString(3)
End If
However, the variable name suggests that it's a date, but you are storing it as string. Use the correct type which is date or datetime. If it's actually a datetime use:
Dim FromToDates As Date
If reader3.HasRows AndAlso Not reader3.IsDbNull(3) Then
FromToDates = reader3.GetDateTime(3)
End If
if you are using Reader.read() then i don't think so you need reader,hasrow(). you can do somthing like this
reader3 = myCommand3.ExecuteReader
If reader3.Read()Then
FromToDates = reader3.GetString(3)
End If
and related to your error its look like you are getting NULL value from database and in vb you can not read NULL, i will suggest to use ISNULL(Column_NAME,'') function in your SQL Script.
It seems that even though the row is empty (all DBNull, perhaps), there IS a row object returning from the query. There are several different solutions presented in this thread that all take differing approaches to catching the empty row before it errors!
http://www.vbforums.com/showthread.php?555183-datareader-and-empty-records
I'm stumped on a problem where VB is removing a row of data upon a simple string assignment. The processing loop is below. If the dvData dataview has 3 rows (i.e., dvData.Count is 3) then the string assignment below is causing the dataview to lose a row (i.e,. after executing the string assignment the dvData.Count is 2). What more odd is that this same string assignment call is used many other times in the same script without causing the loss of a data row.
For Each oneShipment As Shipment In DelShipmentsList
For intRow = 0 To (dvData.Count - 1)
' Example: if dvData.Count is 3 at this point, then....
dvData(intRow)("Result") = " Receipt Transaction Accepted."
' ... now dvData.Count will be 2!
Next
Next
Try examining your RowFilter property for that DataView object. If it's something like this, it would explain the issue:
dvData.RowFilter = "Result NOT LIKE '*Accepted*'"
It looks like we found the answer, albeit completely unforeseen and worthy of much head scratching. Just to be super sure about passing integers and strings explicitly, I had him us CStr() and CInt() where appropriate. Here's what we found:
' This string causes the dataview to change error
dvData(CInt(intRow))(CStr("Result")) = CStr("Receipt Transaction Accepted")
'This string does not.
dvData(CInt(intRow))(CStr("Result")) = CStr("Receipt Transaction Successful")
Apparently there’s something about the word "accepted". We spent quite a while trying different strings to figure out why the Specified string causes the odd behavior that remains otherwise unexplained.
I've been trying so hard to find a solution for this, but no luck. I'm fairly new to VB and SQL, but this shouldn't be too hard. I've inherited a lot of code and there's not too much room to change db attribute types or anything.
I'm trying to run an UPDATE query using parameters in Razor, like so:
Dim updateCommand = "UPDATE [tblJobRating] SET [ProjectManagement] = #0, [ProjComments] = #1, [Schedule] = #2, [SchedComments] = #3 WHERE [JobRatingID] = #4"
All of the columns in question need INT values, but I have one exception where I need to pass it a null value (passing another number or zero won't do). Essentially a "N/A" value for the user.
I assign the variables from Post requests, like so:
Dim projMgmt = Request.Form('projMgmt')
' ...
Dim sched = Request.Form('sched')
I have the "N/A" value posting no value right now (or it can be a string and I can check for IsNumber if need be, I guess). But when I call the query execution, it enters the value as a 0.
db.Execute(updateCommand, projMgmt, projComments, sched, schedComments, ratingId)
It needs to be a NULL value for the backend to work properly. I've tried type checking and passing Nothing, System.Data.SqlTypes.SqlInt32.Null, etc., but it either gives conversion errors or sets to 0. How can I pass it properly?
Edit: I left out the first param in the db.Execute method, passing in the updateCommand. Edited for clarity.
The problem is in your vb variable definition. I assume you have an integer, it needs to be a nullable(of integer) all the way through to the SQL. This can also be written as integer?.
Update
I decided to iterate through the Data.DataTable and trimmed the values there.
Utilizing SirDemon's post, I have updated the code a little bit:
Sub test(ByVal path As String)
Dim oData As GSDataObject = GetDataObj(path)
EmptyComboBoxes()
Dim oDT As New Data.DataTable
Try
Dim t = From r In oData.GetTable(String.Format("SELECT * FROM {0}gsobj\paths ORDER BY keyid", AddBS(path))) Select r
If t.Count > 0 Then
oDT = t.CopyToDataTable
For Each dr As Data.DataRow In oDT.Rows
dr.Item("key_code") = dr.Item("key_code").ToString.Trim
dr.Item("descript") = dr.Item("descript").ToString.Trim
Next
dataPathComboBox.DataSource = oDT
dataPathComboBox.DisplayMember = "descript"
dataPathComboBox.ValueMember = "key_code"
dataPathComboBox.SelectedIndex = 0
dataPathComboBox.Enabled = True
End If
Catch ex As Exception
End Try
End Sub
This works almost as I need it to, the data is originally from a foxpro table, so the strings it returns are <value> plus (<Field>.maxlength-<value>.length) of trailing whitespace characters. For example, a field with a 12 character length has a value of bob. When I query the database, I get "bob_________", where _ is a space.
I have tried a couple of different things to get rid of the whitespace such as:
dataPathComboBox.DisplayMember.Trim()
dataPathComboBox.DisplayMember = "descript".Trim.
But nothing has worked yet. Other than iterating through the Data.DataTable or creating a custom CopyToDataTable method, is there any way I can trim the values? Perhaps it can be done in-line with the LINQ query?
Here is the code I have so far, I have no problem querying the database and getting the information, but I cannot figure out how to display the proper text in the ComboBox list. I always get System.Data.DataRow :
Try
Dim t = From r In oData.GetTable("SELECT * FROM ../gsobj/paths ORDER BY keyid") _
Select r
dataPathComboBox.DataSource = t.ToList
dataPathComboBox.SelectedIndex = 0
'dataPathComboBox.DisplayMember = t.ToList.First.Item("descript")
dataPathComboBox.Enabled = True
Catch ex As Exception
Stop
End Try
I know that on the DisplayMember line the .First.Item() part is wrong, I just wanted to show what row I am trying to designate as the DisplayMember.
I'm pretty sure your code tries to set an entire DataRow to a property that is simply the name of the Field (in a strongly type class) or a Column (in a DataTable).
dataPathComboBox.DisplayMember = "descript"
Should work if the DataTable contains a retrieved column of that name.
Also, I'd suggest setting your SelectedIndex only AFTER you've done the DataBinding and you know you actually have items, otherwise SelectedIndex = 0 may throw an exception.
EDIT: Trimming the name of the bound column will trim just that, not the actual bound value string. You either have to go through all the items after they've been bound and do something like:
dataPathComboBox.Item[i].Text = dataPathComboBox.Item[i].Text.Trim()
For each one of the items. Not sure what ComboBox control you're using, so the item collection name might be something else.
Another solution is doing that for each item when it is bound if the ComboBox control exposes an onItemDataBound event of some kind.
There are plenty of other ways to do this, depending on what the control itself offers and what you choose to do.
DisplayMember is intended to indicate the name of the property holding the value to be displayed.
In your case, I'm not sure what the syntax will by since you seem to be using a DataSet, but that should be
... DisplayMember="Item['descript']" ...
in Xaml, unless you need to switch that at runtime in which case you can do it in code with
dataPathComboBox.DisplayMember = "Item['descript']"
Again, not 100% sure on the syntax. If you are using a strongly typed DataSet it's even easier since you should have a "descript" property on your row, but given hat your error indicates "System.DataRow" and not a custom type, I guess you are not.
Because I can't figure out the underlying type of the datasource you are using I suggest you to change commented string to
dataPathComboBox.DisplayMember = t.ElementType.GetProperties.GetValue(0).Name
and try to determine correct index (initially it is zero) in practice.