?
Solved

VB OracleDataReader

Posted on 2009-07-07
4
Medium Priority
?
473 Views
Last Modified: 2012-05-07
I am selecting a single row that will return a single value. I need to assign that value to a variable of type integer. How can I do this?
The code below is crashing at:
Dim dr As OracleDataReader = myCmd.ExecuteReader()
with this error:
Connection must be open for this operation

I know I just dont have the syntax right because the connection object is correct right before that line is executed.
Dim intDocID As Integer = Nothing
        Dim myConn As Global.Oracle.DataAccess.Client.OracleConnection = Nothing
        Dim myCmd As OracleCommand = Nothing
        Dim strQuery As String = "SELECT DOC_ID FROM DOCUMENTS WHERE DISPLAY_NAME = '1a' 
 
        Try
            Dim strConnect As String = ConfigurationManager.ConnectionStrings("MYDB").ConnectionString
            myConn = New OracleConnection(strConnect)
            myCmd = New OracleCommand(strQuery, myConn)
            myCmd.CommandType = CommandType.Text
            Dim dr As OracleDataReader = myCmd.ExecuteReader() 
            dr.Read()
 
            intDocID = dr.GetInt16("doc_id").ToString()
        Catch ex As Exception
            Dim statusMessage As String = "DATABASE ERROR retrieving data - " + ex.Message
            Throw New ApplicationException(statusMessage)
        Finally
 
            If Not myCmd Is Nothing Then
                myCmd.Dispose()
            End If
 
            If Not myConn Is Nothing Then
                myConn.Close()
                myConn.Dispose()
            End If
        End Try

Open in new window

0
Comment
Question by:bertino12
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
4 Comments
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 2000 total points
ID: 24794305
myConn = New OracleConnection(strConnect)
myConn.Open()
0
 
LVL 20

Expert Comment

by:alainbryden
ID: 24794310
You never called myConn.Open(), this is likely the cause of the specific error message you got.

--
Alain
0
 

Author Comment

by:bertino12
ID: 24794345
Well I did it like below in another function and it works fine.
 Dim myDT As DataTable = Nothing
        Dim myConn As Global.Oracle.DataAccess.Client.OracleConnection = Nothing
        Dim myCmd As OracleCommand = Nothing
        Dim myDA As OracleDataAdapter = Nothing
        Dim strQuery As String = "SELECT D.DOC_ID, D.DOC_TYPE, D.DISPLAY_NAME, D.SUMMARY, D.HTML_DOC, D.SORTCODE " & _
            "FROM DOCUMENTS D " 
        Try
            Dim strConnect As String = ConfigurationManager.ConnectionStrings("myDB").ConnectionString
            myConn = New OracleConnection(strConnect)
 
            myCmd = New OracleCommand(strQuery, myConn)
 
            myCmd.CommandType = CommandType.Text
 
            myDA = New OracleDataAdapter(myCmd)
            myDT = New DataTable("FindResults")
 
            myDA.Fill(myDT)
 
        Catch ex As Exception
            Dim statusMessage As String = "DATABASE ERROR retrieving Find data (""Find By Text"") - " + ex.Message
            Throw New ApplicationException(statusMessage)
        Finally
 
            If Not myCmd Is Nothing Then
                myCmd.Dispose()
            End If
 
            If Not myConn Is Nothing Then
                myConn.Close()
                myConn.Dispose()
            End If
        End Try

Open in new window

0
 
LVL 27

Expert Comment

by:VBRocks
ID: 24794446
If you are only returning a single value from 1 row, then use the ExecuteScalar method:

    myCmd.Connection.Open()

    Dim myValue As String = myCmd.ExecuteScalar()

    myCmd.Connection.Close()

0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Well, all of us have seen the multiple EXCEL.EXE's in task manager that won't die even if you call the .close, .dispose methods. Try this method to kill any excels in memory. You can copy the kill function to create a check function and replace the …
Article by: Kraeven
Introduction Remote Share is a simple remote sharing tool, enabling you to see, add and remove remote or local shares. The application is written in VB.NET targeting the .NET framework 2.0. The source code and the compiled programs have been in…
Monitoring a network: how to monitor network services and why? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the philosophy behind service monitoring and why a handshake validation is critical in network monitoring. Software utilized …
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …
Suggested Courses

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question