This is some of my code. But how do I populate a datagridview using the datareader.
Dim strSQL As String = "SELECT peopleid,firstnames,surname FROM people;"
Dim cmd As New MySqlCommand(strSQL, con)
'cmd.Parameters.AddWithValue("Parameter1", strName)
Dim reader As MySqlDataReader = cmd.ExecuteReader
and how can I handle null field values.
I am developing a Windows application in Visual Studio 2005, V2.0 using VB.NET.I am coding part of an Emergency Response Information System. On my form, I have two combo boxes (cboBaseStationID and cboPriority). I am trying to populate the datagrid with records from my database based on what is selected in both comboboxes. For the first combobox, the user selects a name so the datagrid must only show records with that name. For the second combobox, this is a little more complicated. There are four emergency priorities in the combobox that the user can choose - 1, 2, 3, 4. In the database, there are different response teams (to be dispatched to these emergencies) and each response team has a grade of either 1, 2 or 3. So a grade 1 team can respond to emergency priorities of 1 and 2.A grade 2 team can respond to emergency priorities of 1, 2 and 3.A grade 3 team can respond to emergency priorities of 1, 2, 3 and 4.
So basically, if the user selects emergency priority of '4', then only grade 3 teams can be displayed. I am using two different tables in the datagrid. The datagrid is populating at the moment, but not based on anything that is selected in the comboboxes. It just displays a lot of duplicates of all the records in the tables. Here is my code so far (this code is on the search button click - I have already loaded items into the comboboxes on the form's load event):
Dim sqlConn As New OleDb.OleDbConnection
Dim sqlCmd As New OleDb.OleDbCommand
Dim sqlReader As OleDb.OleDbDataReader
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I am not sure how to phrase my question properly but I want to achieve something like this.
I have a class named Products public class Products
private ID as Integer
private Name as String
Public Property ProductID()
Get
Return ID
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When I do the same, I am getting an error "Object Reference Not Set to an Instance of an Object.
I am trying to populate a listbox from an access database. It is a scheduling database. First my users pick a room they would like to add an event to, then a date. after the date is selected, id like the listbox to populate with meeting titles corresponding to the date they selected. The code so far looks like this:
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I'm writing my first Vb application and have come to a grinding halt... I've created a windows form which has got a datagridview (which is populated by a tableadapter and a dataset generated from a SQL stored procedure) with two columns (Product and Qty), I'm populating the Product Column using a Stored Procedure, the user then adds the quantity. Once they've finished filling everything out they'll then hit a save button and I then need to insert both columns (along with a reference number which I'm getting from a text box) into a table on a sql server.
View 1 RepliesI just spent over an hour looking up on the internet how to fill a combobox for each row in a datagridview that is unbound. I am adding the rows manually by code. The columns are already there and one of them is set to a combobox.
how to add two items to the combobox? Each row will have the same items available in the combobox.
I have an SQL statement like:
SELECT FNAME, LNAME, CITY from EMPLOYEE
How do I create a multi-dimensional array from a datareader which should store values like:
John, Doe, LA
Mike, Johnson, PASADENA
Freddy, Kruger, Long Beach
I have a problem with my project. here is the problem:
My code for login is as follows:
dim conn as SqlConnection = New SqlConnection("Data Source.................)
dim cmd as SqlCommand = New SqlCommand("Loguser",conn)
cmd.CammandType = CommandType.StoredProcedure
[CODE]...
Now the error i get is that "there is a datareader associate with this connection that need to be closed"
I am working on a project which requires me to connect to a MySQL database. From there I query the database and need to do work on the returned values.
I can query the database just fine. However, now I need to do work on the results. The two columns returned are user_name and user_password. The rows are the user accounts. I would like to take my query results and put each column into its own arrary().
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Instead of writing the results to the console, I would like to write each column to an individual array. Is there an easier way to accomplish this task? Or, what is the code I must place within the loop to do this.
I am doing the basic reading form one table,.it is opening the connection,no problems.i got 5 rows in Categories table with two columns .i got some data as well.using datareader i am trying to read the data.It is not going into while loop
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I m trying to use two datareader in same loop but its not working. Here is the error and code below Error line: DR1 = MyCommand.ExecuteReader()Error message: There is already an open DataReader associated with this Command which must be closed first.
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[code]I am facing difficulty in coding when intRow loop for the 2nd round. Error message "There is already an open DataReader associated with this Command which must be closed " appear in the above red highlight vb.net code.
View 6 RepliesHow can I fill this Percentage array with Sql data reader..
Dim StudentID As Integer = Me.ComboBox1.SelectedValue
Dim Percentage() As Integer
Dim con As New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=D:Database
[code].....
The code works fine, but I don't know if is necessary while sentence, maybe there is another option..
Dim CMD As New OleDb.OleDbCommand
CMD.Connection = otraConexion
CMD.CommandText = "SELECT * from procedencias"
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I use firebird server for 2 years and I used this code
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I've wrote a program designed to loop through a text file containing email addresses and unsubscribe said email addresses in our CRM system. I'm having a problem with the following code...
Do While obj_filereader2.Peek() <> -1
strcuremail = obj_filereader2.ReadLine()
Dim dbqCustNo As String = "SQL CODE HERE - SELECT CUSTOMER NUMBER"
Dim exeCustNo As New SqlCommand()
Dim SQLdr As SqlDataReader
exeCustNo.Connection = ConnStr
[Code] ......
The program is falling over when trying to execute the update commands during the datareader loop, with the fabled 'There is already an open DataReader associated with this Command...' error. This program has evolved as I've found problems/better ways of working, so it might be a case of myself just not using the DataAdapter right - I'm guessing I should be using a function of the open DataReader rather than the ExecuteNonQuery command.
How come my datareader looping at the while loop line it become totally no response and without error eventhough I got use the try catch error catching... it only will hang on after few minute... after few loop. Is it the data reader got time out limit?? If exceed the limit it will no response..? Inside my while loop it do a lot of transaction and each transaction also take quite long time... it will affect?
myCommand = New MySqlCommand("SELECT * FROM stk_cus_inv_hd WHERE DocType=?DocType;", conn1)
myCommand.Parameters.AddWithValue("?DocType", "CS")
myCommand.CommandTimeout = 99999
myReader = myCommand.ExecuteReader
While myreader.read <<---- it jam at here and totally no response my coding... but my interface is clickable...
my lot of work here...
End While
I'm not even sure where to start. I would like to create something like the ADO DataReader but that works in a TCP Client/Server scenario.Basically, in the TCP Client, I want to be able to call a certain command in the TCP Server which will return a DataReader like object, which I can then iterate through such as:
while dr.Read from the client. In each loop, I would parse out the various fields as in a normal DataReader.The reason I want to do this is to gain the inherent efficiency of the DataReader object since it doesn't first load ALL of the data. To my understanding, the typical TCP Client/Server setup using streams, would first load all of the data on the server, then transport ALL of that data to the client for processing. I want to avoid that, and just stream the data as the client requests through the Read() command which means the connection will remain open to the server while the Read() command is being issued by the client, or until explicitly closed by the client.
I have my mysql query selected fields (item_code, item_name, item quantity, item_selltype, item_selldetail) but some of these fields are variants.
Dim sqlConn As String = ("SELECT item_code, item_name, item_quantity, item_selltype, item_selldetail FROM qa_items")
Dim objDataAdapter As New MySqlDataAdapter(sqlConn, objConn)
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I'm new in vb.net ..[code]...
View 7 RepliesI have two DataGridViews in one window. The first one displays 2 columns, itemNo and taskWhen I click on a row in this grid, I want to populate the second grid with corresponding material. It is organized so that the itemNo in grid1 is 1, 2, 3, and so on, and so when a row is clicked, I want grid2 to show data that is 1.0, 1.1, 1.2, 2.0, 2.1 and so on. This data is all available in a table that exists within a dataset. However, tableAdapters do not use the .StartsWith function. I am able to get the information from grid1 when it is clicked on using Me.DataGridView1.CurrentRow.Cells(0).Value.ToString but how can I use this to get the data from the table into grid2
View 1 RepliesI have a DataGridView that I'm trying to populate using a For loop:
Dim serverName As String = SQLServerName + "" + Instance
Dim server As Server = New Server(serverName)
Dim Datatable1 As New DataTable
For Each database As Database In server.Databases
Dim row As DataRow = Datatable1.NewRow
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The DGV has been designed with the designer (columns, layout etc). Using the above the DGV does not populate. I was using a ListView for this but I need images in a subitem so have switched to using a DGV.
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Not sure how to do it with an unbound number of players names and combobox's.
I'm trying to put together a quick example for another thread about treeviews, and I'm getting a problem when I have a recursive routine, getting the message.
Quote:
There is already an open DataReader associated with this Command which must be closed first.
I'm a tad confused as I am explicitly creating a new command every time through the loop, so I'm not sure (unless its something ADO is doing behind the scenes) how the datareaders higher up the tree are interfering.
Here's my code :
Private Sub SetupChildren(ByVal ParentID As Integer, ByRef ParentNode As TreeNode)
Dim MyCommand As New SqlCommand("SELECT * FROM Groups WHERE ParentGroup=@ParentGroup", m_myConnection)
[Code]...
Obviously I could close the data reader down before calling the next level of recursion but it would prevent the code continuing the loop at the current level when it had finished processing children.
I was just handed a VB.NET prototyping effort, and I'm not very experienced with VB.NET.I had to create a stored procedure which returns a self-referential table in order. Once, I completed that I wanted to get a DataGridView to show the results.
Previously, my team has been doing a lot of this via the GUI designer of VB.NET so I don't have a ton of code to describe, unfortunately.I was trying to follow their pattern which I will briefly describe here:
I have a DataGridView whose DataSource property points to a BindingSource. The BindingSource points to a DataSet. The editor for that DataSet calls a TableAdapter which gets the data from the stored procedure.
I previewed the data for the TableAdapter. The data is there. On frmMain's load the TableAdapter's Fill command is run. Not seeing anything. And my hunch is that this is way too complex a process to be correct. Or maybe not. I did a lot of Google searches before I decided to bother you fine folks.
Using SQL Server 2008 I created a Stored Procedure called MyStoreProc and it runs fine from the Management Tools.
In VB.Net 2008 I created a new dataset and a new TableAdaptor. In this table adapter I created a new Query called FillByGrid and selected the Stored Procedure. Previewed data and it previewed correctly.
On a form I created DataGridView and selected the Table Adapter from the dataset.
I ran the app and no data is shown. Visual Studio autocreated the code below and I changed it to select the the Query I just created:
Me.MyTableAdapter.FillByGrid(Me.MyDataset.MyTableAdaptor)
No data is shown on the grid so I tried the manual approach:
' Create the dataset
Dim da As New SqlDataAdapter, ds As New DataSet
Dim conn As New SqlConnection
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Still no data shown. However stepping through the I can see that the connection is open, and "da.Fill(ds, "tbl1")" takes a little bit of time as it is running the Stored Procedure and ds table has the correct number of rows and columns. Its just not being shown on the datagrid.
Creating another table adapter in the dataset and returning data from a database table using a standard select * from table command display in the datagridview fine.
I am trying to auto populate some fields in my datagridview on my form called frmInfo.
I will try to explain what I need. The main form of my project is called frmEntry. frmEntry is mainly a data entry form only. A binding navigator is present to navigate between different record stored in the database. I want the datagridview on frmInfo to "grab" info present in the text fields of frmEntry.
I am trying to click a checkbox in the datagridview to automatically populate a textbox in the same datagridview with the current date/time.
I have the following code which gives the error
Private Sub DgvReturns_CellClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DgvReturns.CellClick
If e.ColumnIndex = 4 Then
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Im new to vb.net and would like to know the very basics on how a datagridview works? how does it populate data from the database? what process does vb follow to update this datagridview? I'm trying to get my head around the following terms and need some explaining how they work and how they are linked? if possible, is there a link to a diagram that explains this?
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I'm connecting a MS-SQL remotely with VB2008 Express.I defined two different methods - the first one is copied from my old VB6 application, which is working perfectly.In this application, the retrieved data is added to a listview control, not datagrid!
Code:
Dim myconn As ADODB.Connection
Dim MyRecSet As ADODB.Recordset
myconn = New ADODB.Connection
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The SQL query contain several table, thus I used a "*" instead for the table name- not sure this is correct?
Code:
da.Fill(ds,"*")