I have the following code;
Dim rdr As SqlCeDataReader = cm_sel.ExecuteReader
If rdr.HasRows Then
While rdr.Read
Documents.DeleteDocument(rdr.Item("fID"))
End While
End If
The error I get is:
SQL Server Compact does not support calls to HasRows property if the
underlying cursor is not scrollable.
So how am I supposed to check if data exists before actually reading the DataReader?
EDIT
the whole code:
Dim con As New SqlCeConnection(ConfigurationManager.ConnectionStrings("MyConnectionString").ToString)
Dim cm_sel As New SqlCeCommand("SELECT fID FROM Files WHERE fCatID=" & catID, con)
Try
con.Open()
Dim rdr As SqlCeDataReader = cm_sel.ExecuteReader
If rdr.HasRows() Then
While rdr.Read
Documents.DeleteDocument(rdr.Item("fID"))
End While
End If
Return "{'result':'ok'}"
Catch ex As Exception
Return "{'result':'error'}"
Finally
con.Close()
con.Dispose()
End Try
You could call directly reader.Read since will return false if there are no rows. Simply remove the if statement surrounding the while.
UPDATED CODE:
Dim rdr As SqlCeDataReader = cm_sel.ExecuteReader
While rdr.Read
Documents.DeleteDocument(rdr.Item("fID"))
End While
This works fine for the above problem.
Dim hasrows As Boolean
hasrows = False
While (rdr.Read())
hasrows = True
End While
If (hasrows) Then
--do something
else
--do something else
end if
If you assign hasrows function to any Boolean and try to use it, the reader can jump to second record. The above solution will avoid that scenario as well.
Related
This function seems to be running the SQL query twice, any idea why?
When I run an insert SQL query it inserts the data but also brings back this error:
Violation of PRIMARY KEY constraint 'PK__SD_T_Cod__143F51C51BFD2C07'.
Cannot insert duplicate key in object 'dbo.SD_T_Code'. The duplicate
key value is (t-503).
This seems to tell me that it is running the SQL twice, it gets inserted the first time, but the second time it doesn't insert because the id already exists (it got created with the first insert)
Public Function InsertUpdateData(ByVal cmd As SqlCommand) As Boolean
Dim connStr As String = ConfigurationManager.ConnectionStrings("dbConnect").ConnectionString
Dim con As New SqlConnection(connStr)
cmd.CommandType = CommandType.Text
cmd.Connection = con
Try
con.Open()
cmd.ExecuteNonQuery()
Return True
Catch ex As Exception
Response.Write(ex.Message)
'resultSQL.Text = ex.Message
Return False
Finally
resultSQL.Text = "Successfully Saved"
con.Close()
con.Dispose()
End Try
End Function
End Class
I've been searching the depths of the internet and all the solutions I found did not solve this problem.
I am using Visual Web Developer 2010 Express with SQL Server 2008, using VB.
I am trying to execute a stored procedure to insert some data coming from a textbox control to a database, if the id doesn't exist it inserts both the id given in the textbox and the current date (time_scanned_in), if the id exists already, it will insert the current datetime in the [time_scanned_out] column, if all 3 fields in the db are full, it will return #message = 1.
Here is the sql stored procedure:
ALTER PROCEDURE dbo.InsertDateTime
#barcode_id nchar(20),
#message char(1) = 0 Output
AS
BEGIN
if not exists(select * from tblWork where barcode_id = #barcode_id)
begin
INSERT INTO [tblWork] ([barcode_id], [time_scanned]) VALUES (#barcode_id, GetDate())
end
else if exists(select * from tblWork where barcode_id = #barcode_id AND time_scanned_out IS NOT NULL )
begin
SET #message=1
end
else if exists(select * from tblWork where barcode_id = #barcode_id AND time_scanned_out IS NULL)
begin
UPDATE [tblWork] SET [time_scanned_out] = GetDate() WHERE [barcode_id] = #barcode_id
end
RETURN #message
end
If I execute this (by right clicking on the SP), it works flawlessly and returns the values when all fields have been filled.
But when executed through the vb code, no such procedure can be found, giving the error in the title.
Here is the vb code:
Dim opconn As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"
Dim sqlConnection1 As New SqlConnection(opconn)
Dim cmd As New SqlCommand
Dim returnValue As Object
cmd.CommandText = "InsertDateTime"
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = sqlConnection1
sqlConnection1.Open()
With cmd.Parameters.Add(New SqlParameter("#barcode_id", TextBox.Text))
End With
With cmd.Parameters.Add(New SqlParameter("#message", SqlDbType.Char, 1, Label3.Text))
End With
returnValue = cmd.ExecuteScalar()
sqlConnection1.Close()
Note, I haven't done the code for the return part yet, will do that once I get it to locate the SP.
Tried listing all objects with the sys.objects.name for each of the databases in a gridview, it listed everything but the stored procedure I want.
Why is this, any ideas? Would be much appreciated, spent hours trying to find a solution.
If anyone needs any more code or information feel free to ask.
try cmd.parameters.clear() first and then start adding parameters in cmd object. also instead of cmd.executescaler(), try cmd.executenonquery or cmd.executeReader()
Try this
cmd.Parameters.AddWithValue("#barcode_id", TextBox.Text)
SqlParameter prmOut = cmd.Parameters.Add("#message",SqlDbType.Char, 1)
prmOut.Value = Label3.Text
prmOut.Direction = ParameterDirection.InputOutput
cmd.ExecuteNonQuery()
returnValue = prmOut.Value.ToString()
Recreated the whole project with a whole new database, copied all the same code, and now it all works flawlessly! Still have no idea what was wrong, but thank you all, you were all prompt and knowledgable.
Here was the final VB code for anyone who's interested:
Dim myConnection As New SqlConnection(opconn)
Dim cmd As New SqlCommand()
Dim myReader As SqlDataReader
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = myConnection
cmd.CommandText = "InsertTimes"
cmd.Parameters.AddWithValue("#message", OleDbType.Integer)
cmd.Parameters.AddWithValue("#barcode_id", TextBox.Text)
cmd.Parameters("#message").Direction = ParameterDirection.Output
Try
myConnection.Open()
myReader = cmd.ExecuteReader()
Dim returnMessage As String = cmd.Parameters("#message").Value
If returnMessage = 1 Then
label_confirmation.Text = "Record successfully submitted!"
TextBox.Text = ""
ElseIf returnMessage = 2 Then
label_confirmation.Text = "A finish time already exists for the record '" & TextBox.Text & "', would you like to override the finish time anyway?"
button_yes.Visible = True
button_no.Visible = True
ElseIf returnMessage = 3 Then
label_confirmation.Text = "Record submitted, work operation status complete!"
TextBox.Text = ""
End If
Catch ex As Exception
label_confirmation.Text = ex.ToString()
Finally
myConnection.Close()
End Try
i have this code to update a database, but when ever i run it with the right data, it executes without errors but the databse is not update
Dim conn As New SqlClient.SqlConnection(My.Resources.conn_str)
Dim SQL As String = "Update vehicle SET make=#make,reg_no=#reg_no,model=#model,year=#year,type=#type,last_service=#last_service Where (id = #id)"
conn.Open()
Try
Dim cmd As New SqlClient.SqlCommand(SQL, conn)
Try
cmd.Parameters.AddWithValue("#make", strMake)
cmd.Parameters.AddWithValue("#reg_no", strRegnNum)
cmd.Parameters.AddWithValue("#model", strModel)
cmd.Parameters.AddWithValue("#year", intYear)
cmd.Parameters.AddWithValue("#type", strType)
cmd.Parameters.AddWithValue("#last_service", LastService)
cmd.Parameters.AddWithValue("#id", ID.ToString)
cmd.ExecuteNonQuery()
cmd.Dispose()
Catch ex As Exception
Return ex.Message
End Try
Catch ex As Exception
Return ex.Message
Finally
conn.Dispose()
End Try
can anyone help me with the reason its not working, as i don get an error message?
thanks
EDIT
i replaced the cmd.ExecuteNonQuery() with
Dim intAffected As Integer = cmd.ExecuteNonQuery()
Debug.Print(intaffected)
and i get 1 in the output window
A few thoughts:
If you have access to SQL Profiler, you can see the query, the values, the result, any triggers, any transactions, etc. This is the easiest way to identify what is going on.
If you don't have access to Profiler, update your query to include the OUTPUT clause, and return the values from inserted.* and deleted.* into a SqlDataReader using ExecuteReader. Check the results.
If the id is an int, don't use ID.ToString() on the parameter.AddWithValue. Use the integer itself, as the AddWithValue method with a string value could cause the ID parameter to be configured as a varchar/nvarchar.
I have the below mentioned code in a seperate class file for establishing connection and carry out DB transactions. I have an issue where multiple connections being opened which sometime exceed the connection pool. When I stepped through the code I found that there are codes which call ConnectDB() in a loop without calling DisconnectDB(). But I expected that the condition OraConn.State = ConnectionState.Closed should handle the situation. Somehow the condition is always satisfied hence openning another set of connection. Can you suggest where am I going wrong and also what best practice can be adopted here?
Public Class Connection
Dim Str_conn As String = "Data Source=...; User=...; password=...; Min Pool Size=10; Max Pool Size=500;"
Public OraConn As OracleConnection
Dim cmd As OracleCommand
Dim dr As OracleDataReader
Dim data_adapt As OracleDataAdapter
Dim dt As DataTable
Dim ds As DataSet
Public Sub ConnectDB()
OraConn = New OracleConnection(Str_conn)
If OraConn.State = ConnectionState.Closed Then
OraConn.Open()
End If
End Sub
Public Sub DisconnectDB()
If OraConn.State = ConnectionState.Open Then
OraConn.Close()
End If
End Sub
Public Function get_dataset(ByVal query As String, ByRef ds As DataSet) As DataSet
data_adapt = New OracleDataAdapter(query, OraConn)
data_adapt.Fill(ds)
Return ds
End Function
Public Function get_datareader(ByVal query As String) As OracleDataReader
cmd = New OracleCommand(query, OraConn)
dr = cmd.ExecuteReader()
Return dr
End Function
Public Sub UpdateDB(ByVal query As String)
cmd = New OracleCommand(query, OraConn)
cmd.ExecuteNonQuery()
cmd.Dispose()
End Sub
The class is refered in other classes or directly in the aspx.vb pages like this.
Public Function InsertData(ByVal var1 As String, ByVal var2 As String) As Integer
conn.ConnectDB()
Dim qryInsert As String
qryInsert = " INSERT INTO TABLE VALUES ('" & var1 & "', "
qryInsert = qryInsert & var2 & "')"
Try
conn.UpdateDB(qryInsert)
Catch ex As OracleException
If ex.Code = 1 Then
updData(var1, var2)
ElseIf ex.Code = 2091 Then
msgprompt("Duplicate Unique Key!", "Warning")
End If
Finally
conn.DisconnectDB()
End Try
Return count
End Function
The connection is again opened in function updData(). While I understand that it has to be closed correctly but keeping tab on every developer is not possible. Hence I want to control it directly from the connection class by using the same connection but the condition If OraConn.State = ConnectionState.Closed is not helping.
UPDATE
I have put the code in UpdateDB under a Using block and removed call to ConnectDB and DisconnectDB from function like InsertData(...). It seems that the issue has been resolved. But I would like to know in case of exception will the connection remain open? and also OraConn is a public variable defined outside Using block so will it be disposed of by the GC?
Public Sub UpdateDB(ByVal query As String)
Using OraConn = New OracleConnection(Str_conn)
cmd = New OracleCommand(query, OraConn)
Try
OraConn.Open()
cmd.ExecuteNonQuery()
Catch ex As Exception
Throw
Finally
cmd.Dispose()
End Try
End Using
End Sub
You must close all the connections as soon as you are done with it, no matter what.
Suggestion:
The best practice for closing the connection is to do it in finally block. So that even if there is any error, catch it (log it if required) in catch block, and then connection will get close in finally block.
UPDATE
You can put one private static counter in your Connection class. When ever ConnectDB() is called you increment this counter and decrement it in every DisconnectDB(). Now in ConnectDB() you check the value of counter, if it exceeds a minimum threshold you throw error, by doing this way; you can come to know idle connection present in your code and refactor it. On production keep this threshold value high or ignore it in code.
In my codebehind I have this vb:
Dim reader as idatareader = includes.SelectDepartmentID(PageID)
While reader.Read
Did = reader("departmentid")
GroupingHeading = reader("heading")
Folder = reader("folder")
If reader("OwnBanner") Is DBNull.Value Then
OwnBanner = String.Empty
Else
OwnBanner = reader("ownbanner")
End If
Then in my class I have:
Public Function SelectDepartmentID(ByVal PageID As Integer) As IDataReader
Dim Command As SqlCommand = db.GetSqlStringCommand("sql")
db.AddInParameter(Command, "#pageid", Data.DbType.Int32, PageID)
Dim reader As IDataReader = db.ExecuteReader(Command)
reader.Read()
Return reader
End Function
No Errors are being presented yet nothing is being returned by the reader. Is there an error in my code?
Thanks.
Try removing the
reader.Read()
line from SelectDepartmentID.
You are skipping the first row of the reader. Remove the reader.Read() statement in the SelectDepartmentID function just prior to the return statement.
Any function that returns a reader should make no assumptions about what the calling code will do with it and just return it unmodified.