Struggling again with doing in VB what I find simple in TSQL (sigh) - hoping that a forum member can point me in the right direction again. I have a datatable with three columns :- A, B & C I am looking to count the number of records in the datatable where columns B & C (both numeric) match specific criteria. eg :-
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In my datatable I have a single column containing a series of integer values. eg:-
1
2
3
1
2
2
2, etc
I am looking to do an equivalent of the following SQL statement :-
Select Value, Count(Value) as Total
From DataTable
Group By Value
Order by Value ASC
I'm looking to return the following from the above example :-
Value Total
1 2
2 4
3 1
I added this lines in the form load of DataGridPrinter by Merrion in the codebank..[code]Unable to cast object of type 'System.Data.DataViewManager' to type 'System.Data.DataTable'.
View 2 Repliesevery time i run this code i get the same error
Unable to cast object of type 'System.Data.DataTable' to type 'System.Data.DataView'.
the code is
Dim plmExcelCon As New System.Data.OleDb.OleDbConnection
Dim cmdLoadExcel As System.Data.OleDb.OleDbDataAdapter
Dim PrmPathExcelFile As String
[Code]......
I get the below error Unable to cast object of type 'System.String' to type 'System.Data.DataTable'.This is the code I'm using
Dim str As String = String.Empty
If (Session("Brief") IsNot Nothing) Then
Dim dt As DataTable = Session("Brief")
If (dt.Rows.Count > 0) Then
[code]....
Declare some class level variables that will keep track of the sums for each column. For example:
[Code]....
During the RowDataBound event, retrieve the data from each column and add it to the appropriate sum. I'm not sure if you are developing an ASP.NET application or a Win-forms desktop application so I cannot help you any further at this point. What have you tried so far to solve the problem?
How to make the data in the DataTable automatically change when there is the Insert, Update or Delete.my code like this:
VB.NET
Imports System.Data
Imports System.Data.OleDb
[code].....
I have the following DataTable:
Date
08/06/2008
09/06/2008
04/06/2008
08/06/2008
[Code].....
I'm loading a DataGridView from a DataView which collects data from a DataTable. I use the DataView to filter, this is the
Dim dv As New DataView
dv = DataSet4.Tables("TABLA1").DefaultView
dv.RowFilter = "propietario='" + NombrePro + "'"
[code].....
I am wondering if it is possible to filter data from a datatable.Sample datatable
Quote:
Sno CatID Nos
1 XYZ 25
[code].....
i encounter this error while passing a string as datatable.
I populate combobox1 with tables/sheets from excel and each table has datarows which i want to get the data and import to sql corresponding table, so, I declare
Dim XLSTableName as String = Combobox1.SelectedItem
And I encounter the this error : Conversion from type 'DataTable' to type 'String' is not valid
how do i return the combobox1.SelectedItem as Datatable cos if i declare
Dim XLSTableName as DataTable and pass it to the select Command thus:
Dim objCmdSelect As New OleDbCommand("SELECT * FROM [" & XLSTableName & "], ODBConn)
to obtain the dataRows I got the following error: operator '&' is not defined for types 'String' and System.Data.DataTable'
I write the code below. I want to make short using linq count.
Dim query0 = From obj In dtAginglist _
Where (obj.Field(Of String)("CurrentStatus") = "Open" Or obj.Field(Of String)("CurrentStatus") = "Acknowledge") _
[Code]....
I try to use code below but it dosen't work with if source is datatable.
Dim orderCounts = From c In customers New With { _
c.CustomerID, Key .OrderCount = c.Orders.Count() }
I have a DataTable that has several hundred rows.I want to get a row count of distinct values in a particular column.For example, I have a DataTable of Product Orders, but I want to get the number of unique Customers.
I was using this code, but I can't rely on it because my binding source is filtered from time to time.If my binding source has filtered out all rows datatable.DefaultView returns 0 rows.
I'm pulling data from my DB, adding it to a DataTable and binding that DataTable to my DataGridView. Before I bind the data, I need to change/remove some data. When I loop through the rows and use a Select Case, just for this column, it doesn't work. But if I use an If, it works fine. [Code] In the example above, the "Pass_Flag" row works just fine, but the "FailureCD" does not. But after the Select, with the If statement, it works. In the example, I'm casting the row as a string first and then an integer. I tried casting to an integer in the select case and it doesn't work either.
View 4 RepliesFor each column in data table i want to add parameter with same data type as column data type. But looks it's not that simple.
Dim cmd As New SqlCommand
Dim dType As New System.Data.SqlDbType
For Each cl As DataColumn In DataTable1.Columns
[CODE]...
How can I do this?
im trying to use this select statement on a OLEDB database and im am getting a data type mismatch.[code]its not just this particular select statement. its any where the where clause is dependant. in the past i have got round this by passing in a parameter but its not my prefered method and id really rather not pass in two dates as parameters.i have looked in to this and found some thing that said that in oledb select commands you need to CONVERT the dates however when i trid that i got an error thar says somthing like CONVERT is not a recognised function.
View 5 RepliesI've spent a substantial amount of time trying to figure this out, but I keep getting the same error
A first chance exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
A first chance exception of type 'System.NullReferenceException' occurred in project1.exe
This happens when I try to use the DataReader.my code is
Public Function Identification() As List(Of Integer)
Dim returnIndex As New List(Of Integer)
Dim dbCount As String = "SELECT Bookingid FROM bookdetail WHERE Date =" & getCurrentTimeString() & " 12:00:00 a.m."
Dim count As Integer = 0
[code]....
I need to create a function which have either 1 parameter with a string as data type or 2 parameters with double as data type.Something like the substring method.
View 2 RepliesI have data that I want to store in some type of variable where I can easily access when needed. For example I have:
google.com -> This is a cool website.
yahoo.com -> News website
gmail.com -> Mail website
I want to be able to store those in some type of group so if I go like:
get data of google.com without going through a loop.
I'm working on a small project - a database program to track and log the progress of some experiments. I'm using VB 2010 Express, and I'm pretty much just learning as I go. I'm getting ready to learn about the data models available, and am having trouble navigating the info I find.Is it best to develop the data within the SQL CE environment, or does that require the end-user to download additional libraries/programs? Is there a better data model for my needs (not much complex data processing, but a sizable amount of records/tables)?
View 2 RepliesI am working on a project that takes an xml schema and xml data files and places them into a DataTable, the 2 files are generated from a working table that i have written to disk. I wish to load these 2 files into a DataTable. Here is What i have
vb.net
Friend Function CreateTable(ByVal tableName As String) As Boolean
Dim table As New DataTable(tableName)
table.ReadXmlSchema(tableName & ".xsd")
[code]....
this however produces the following error on line 3
Quote:
System.ArgumentException was unhandled Message=DataTable 'get_item_list' does not match to any DataTable in source.
get_item_list is the parameter passed into this function (tableName)
I have a datatable that has a resource in one field and hours used in another, it looks like this -
Resource Hours Used
Manager 1
Accountant 1
Field Staff 2
Accountant 3
Manager 4
Manager 1
Administrator 6
Field Staff 4
Manager 0.5
Administrator 1
What I want to do is be able to create a summary of the data table above that groups multiple occurrences of a resource and adds up the hours used for that resource, creating a summary that looks like this -
Resource Hours Used
Manager 6.5
Accountant 4
Field Staff 6
Administrator 7
I'v designed a ms access database table with one field having Datetime datatype. I can Insert data into it from vb.net front end by trns_dt DateTime.Now.DateBut when I fetch records from the tableand assign the dataset datasource as da, it shows datatype mismatch error.
daleDbDataAdapter("SelectDaily_Transactiondtp_from_dt.value dtp_To.value con)
dsDataSet
[code].....
So that error doesn't really make since. I mean I know what the error means but my query looks good and is what I expected.Is there any way to see the final outcome from SQLInsert. Parameters.AddWithValue..Before it gets to "SQLInsert.ExecuteNonQuery()" ??
View 3 RepliesI've got the following code to search for data from my database, but when I run the code its giving me a 'Data type mismatch in criteria expression.' but I cant for the life of me work out why
To fill my table I use: OleDbDataAdapter1.Fill(TAS_DataDataSet)
Then use the following to try and search for data by the employee ID;
Private Sub comboEmployee_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles comboEmployee.SelectedIndexChanged
Dim EmployeeID, SQLString As String
[Code]....
What is the numeric data type that can hold the biggest Integer in VB.NET 2010?
View 5 Replieshow to copy data from datatable to table in dataset i ry this but its readonly property
ds.datatable1=newdt.copy
I am updating a data table (dt_report_crypt) from an encrypted csv file in the code below:I decrypt the colums and update the same dreport_crypt, such that it will contain de-crypted data.This part is working wellI however need to use this de-crypted datatable as a data source to update a second table(dt_report), using the sql SELECT command to filter relevant data,
Dim dt_report As DataTable
Dim dt_report_crypt As DataTable
Using cn As
[code].....
I'm getting a very odd problem with a conversion from C# to VB (VB10 - .NET 4 target):
C#: IEnumerable<string> test = new string[] { "abc", "def", "ghi" };
int i = test.Count<string>();
VB:Dim test As IEnumerable(Of String) = New String() { "abc", "def", "ghi" }
Dim i As Integer = test.Count(Of String)()
the last line results in a compile error "overload resolution failed because no accessible 'Count' accepts this number of type arguments"
[Code]...
I wanted to know what (if any) differences there are to using the SQL Transaction within the application versus written into the stored procedure using TSQL statement. We would need to restructure the stored procs and vb code to get this to work and I'm not sure it would be worth the effort at this time.
Public Sub RetrieveTData(ByVal cID As String, ByVal cnn As SqlConnection) As Boolean
Dim sqlTran As SqlTransaction
cnn.Open()
sqlTran = cnn.BeginTransaction
[code].....
We aren't certain whether the timeout is occurring in DataAlreadyTransferred() or usp_BigNasty_CopyDataFromDB1toDB2 due to how the try/catch is written. We can restructure this code, but will take a week or so to get it to production (no errors occur on test/dev today)
DB1 - permanent storage, used by other applications as well
DB2 - working set, used only by Web App
DataAlreadyTransferred(cID) first checks to see if DB2 has any copies of the records, if DB2 does and those records are clean it deletes them (data could have changed in DB1 and we want the most up-to-date version). If DB2's data is dirty it is left alone and no data is deleted.
usp_BigNasty_CopyDataFromDB1toDB2 copies rows from approximately 20-30 different tables and copies over the perm copies from DB1 into DB2, essentially creating a working set from which the Web App can access
We are aware this is inefficient and are examining ways to improve it, just haven't had time yet... I believe by having the transactions in the app code it's locking many more tables than is really needed. If we move them to the stored procs, less tables will be locked at one time thus improving our chances of removing deadlock conditions/timeout issues we're seeing today. Just not sure on this..
