VS 2008 Using A DataReader
Jan 27, 2010
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().
[code..]
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.
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Feb 20, 2012
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
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Aug 17, 2009
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"
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Oct 15, 2010
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
[Code]...
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Feb 7, 2010
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.
[Code]...
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Mar 29, 2009
[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.
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Jan 11, 2011
How 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].....
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Mar 16, 2010
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"
[Code]....
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Feb 19, 2010
I use firebird server for 2 years and I used this code
[Code]...
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May 14, 2008
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.
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Apr 28, 2011
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.
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Sep 9, 2009
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
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Jun 2, 2010
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.
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Jun 26, 2009
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.
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Jan 22, 2011
I am trying to retrieve the data from EXCEL 2003 spreadsheet from row 8 onwards because from Row 1 to Row 7 the row is merged columns from A1 to K1, A2 to K2, A3 to K3, A4 to K4, A5 to K5, A6 to K6, A7 to K7.
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Jun 22, 2010
i am working on a search feature for a program i am working on and i found a tutorial online that provides some insight but the actual code, after being modified to fit my aplication, does not work. i get two different errors as of right now, one that tells me "the value of type 'System.data.sqlclient.sqldatareader' cannot be converted to '1-dimensional array of system.data.sqlclient.sqldatareader" and the other that says"argument not specified for parameter 'array' of 'Public shared function... anyway i am kinda new to this and here is what i have so far. any advice?
Private Sub SearchOKButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SearchOKButton.Click
[Code]...
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Mar 30, 2011
I have the following code which does what it's supposed to do:
objSQLCommand = New SqlCommand("select * from table1", objSQLConnection)
objSQLCommand.Connection.Open()
objSQLDataReader = objSQLCommand.ExecuteReader()
While objSQLDataReader.Read()
[Code]....
But I need to loop through the objSQLDataReader 1 more time. How would I do that?
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Jul 6, 2011
I got the error message There is an open data reader associated with this command which needs to be closed first by using the following code:
myCommand = New SqlCommand("SELECT BookCode FROM tblBook",myConnection)
myReader = myCommand.ExceuteReader
While myReader.Read
[Code]...
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Jun 10, 2011
I am copying sample.csv file's content into the new.csv file. But I need to add additional column in new.csv file which holds the default value as "Yes" for each row that exists in old file. Here is the code I have written.
Dim ioFile As New System.IO.StreamReader("C:sample.csv")
Dim ioLine As String
Dim ioLines As String[code].....
The first four columns ID,Name,Number,Amount are present in sample.csv.I am adding additional column Copied which should be "Yes" for each row.
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Mar 18, 2009
If my Select statement finds data that matches the criteria, how do I get myReader (DataReader) to read each record when there are more then one record found?
Dim myReader As MySql.Data.MySqlClient.MySqlDataReader
myReader = myCommand.ExecuteReader()
If myReader.Read() Then
[code]....
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Sep 21, 2009
I am trying to tag of some words.There are 5 tag word in my database. but only the first record is coming.i want to
my codes
Public Function tags(ByVal ID As Integer) As String
[code].....
my html code in gridview <%#tags(Container.DataItem("ID"))%>
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Apr 26, 2011
Hey Friend i am using a form with a *combobox*in which the items i have taken from the
sqldatabase named as balance and that sqldatabase have two columns one is customername and the
another is obbalance now .
In the form i had binded all the customer names from the table and now i have a textbox i want to do is
when the user selects the combobox.selected item any one customer name i need to display the obbalance of the selected customer in tat textbox
[Code]...
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Dec 12, 2009
two DataReader in one TreeView ?
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Aug 25, 2010
i want to fill a Datatable with a Datareader row by row but get an exception because the reader's columns have a different order than the Datatable's columns.
Why and how does a Datatable loads itself with a Datareader correctly, even so it has a column collection with different order?
I need to calculate values for every row so i dont want to load the Datatable completely but row for row. It has 25 columns so i dont want to set it all manually.
There must be a chance to load/fill/add a new row from a datareader without having the same column order(reader.GetSchemaTable?).
Following is what i have but what doesnt work:
Using reader As System.Data.SqlClient.SqlDataReader = command.ExecuteReader
'next line works(configInfo.DataSource is a Datatable)but is inappropriate
configInfo.DataSource.Load(reader)
[Code].....
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Jun 22, 2011
I have this sub as part of my login / logout system. When this sub is called to login users it works perfectly, but on logout it throws an error that doesn't make any sense to me.
[Code]...
This sets a nonsense email address so that when validate_session searches for a valid email/session combo in the db it trips the destruction of the sensitive session data.
The question boils down to this: Why is the error being thrown when the logout sub calls validate_session?
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Mar 6, 2012
Is there an easy way to reset or clear a DataReader so it can be read through more than one time? I found a Close method but not an open method.
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Nov 10, 2010
I have a few Oracle procedures that generate/return a large amount of data that I need to write out to a file.I'm currently trying to accomplish with a data-reader. It seems to be working, I've successfully generated a 479mb file without any trouble.It took less than 4 minutes from the time I retrieved the dataReader to complete the file.But the dataReader I get for a particular procedure is crawling.It's unbelievably slow.I modified my code to try and get a better idea of what is going on[code]I'm writing a PL/SQL block that will open that cursor to see if the performance issue exists when I remove the .Net code..
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Nov 28, 2009
Again I have problem with checking whether DataReader object has data or not?
Dim cmd as SqlCommand
Dim drd as SqlDataReader
cmd = New SqlCommand ("SELECT * FROM Stock", conx)
drd = cmd.ExecuteReader()
[Code]...
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Aug 1, 2011
This may perhaps be a stupid question but I just can't get it to work.
I have an if clause where I compare a textfield with the value of a datareader.
It looks a little like this if me.txtfield1.text <> reader("field1") OR me.txtfield2.text <> reader("field2") ETC... I do this for a lot of field.
But now I want to check if field2.text is string.empty and if it is I want to skip the comparison for that field.
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Aug 8, 2011
i want to compare two data values in my database.These two dates belong to two different columns.What i want to compare is if the date of one column greater by 6 months from the date of other column then it should give error.I want to pass this query to database and check,and later on depending on the result want to insert my other functionality?
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