Ok i have 2 queries that are running SQL Dependecy's to simulate the push - notifications
really my ownly question is why in heck my 2 pieces of code run so much differently ( slower / faster ) then the other
here is the fast code (milisecond updates)
lbnoes.Text = ""
'You must stop the dependency before starting a new one.
'You must start the dependency when creating a new one.
SqlDependency.Stop(getSQLString())
SqlDependency.Start(getSQLString())
Using cn As SqlConnection = New SqlConnection(getSQLString())
Using cmd As SqlCommand = cn.CreateCommand()
cmd.CommandType = CommandType.Text
cmd.CommandText = "SELECT test1, test2 FROM dbo.[ztest]"
cmd.Notification = Nothing
' creates a new dependency for the SqlCommand
Dim dep As SqlDependency = New SqlDependency(cmd)
' creates an event handler for the notification of data changes in the database
AddHandler dep.OnChange, AddressOf dep_onchange1
cn.Open()
Using dr As SqlDataReader = cmd.ExecuteReader()
While dr.Read()
lbnoes.Text = lbnoes.Text & vbCrLf & (dr.GetString(0) & " " & dr.GetString(1))
'PopupNotifier1.ContentText = dr.GetString(0) & " " & dr.GetString(1)
'PopupNotifier1.Popup()
End While
End Using
End Using
End Using
HERE is the slow code (almost 2 minutes /update or so it seems) it is almost acting like its calling the on changes over and over. - hopefully you can tell me why cause i rather use this piece of code
lbnoes.Text = ""
Try
Dim con As New SqlConnection
Dim myConString As String = getSQLString()
Dim objcommand As SqlCommand = New SqlCommand
'con.ConnectionString = myConString
With objcommand
.Connection = con
Dim cmdText As String = "SELECT test1, test2 FROM ztest"
.CommandText = cmdText
End With
con.ConnectionString = myConString
SqlDependency.Stop(getSQLString())
SqlDependency.Start(getSQLString())
Dim dep1 As SqlDependency = New SqlDependency(objcommand)
AddHandler dep1.OnChange, AddressOf dep_onchange1
con.Open()
Using readerObj As SqlClient.SqlDataReader = objcommand.ExecuteReader
'This will loop through all returned records
While readerObj.Read
Dim t1 As String = readerObj("test1").ToString
Dim t2 As String = readerObj("test2").ToString
lbnoes.Text = lbnoes.Text & vbCrLf & (t1 & " " & t2)
' 'PopupNotifier1.ContentText = dr.GetString(0) & " " & dr.GetString(1)
' 'PopupNotifier1.Popup()
End While
End Using
con.Close()
Catch ex As Exception
End Try
Both on Changes are being invoked the same way ( different invoke methods / removehandles ) ...
Please help this confused nub.
Thanks in advance
Well, it's not easy to tell without going further in the application code, but it's much more efficient to access the datareader members trough index than trough column names.
Also, maybe the type conversion has something to do..
Related
My code for updating mysql table having more than 2000 rows through a loop using VB.net is working fine but too slow. Is there any way to update it faster ? Anybody please help. Thanks. My code is given below.
Dim mysqlconn = New MySqlConnection
mysqlconn.ConnectionString = "server=localhost;user id=root;password=1234;database=Share"
mysqlconn.Open()
Dim adapter As New MySqlDataAdapter("SELECT * FROM name_list;", mysqlconn)
Dim datatable As New DataTable()
adapter.Fill(datatable)
Dim cmd As New MySqlCommand
cmd.Connection = mysqlconn
Dim sql As String
Dim i as integer = 0
While i <= datatable.Rows.Count - 1
Dim sy As String = datatable.Rows(i).Item(3).ToString.Trim
sql = "UPDATE Name_list Set Numerology = '" & "N-" & variable1 & " S- " & variable2 & "',FSTLetter = '" & variable3 & "',Timing = '" & vriable4 & "',P_Numerology = '" & variable5 & "' WHERE Symbol = '" & sy & "'"
sy = ""
cmd.CommandText = sql
cmd.ExecuteNonQuery()
i = i + 1
End While
adapter.Fill(datatable)
DataGridView1.DataSource = datatable
DataGridView1.Refresh()
Don't name variables the same as class names (DataTable, datatable) vb.net is case insensitive so it confuses intellisense.
Database connections and commands need to closed and disposed.
Using blocks do this for you even if there is an error.
You can set the connection string by passing it directly to the constructor of the connection. Likewise, you can set the command text and the connection by passing to the constructor of the command.
Don't open the connection until right before it is used. In this case we don't need a DataAdapter but if you are using one it is not necessary to open the connection at all. The .Fill method of the DataAdapter will open and close the connection. However if the DataAdapter finds an open connection it will leave it open.
To avoid confusion, I created 2 data tables. I used a single connection but I opened and closed it each time it is used. It is not disposed until the last End Using.
The first command retrieves only the sy column. Replace Column4_Name with the actual column name. We don't want to pull down data we don't need so no Select *.
Always use parameters to avoid sql injection which can damage your database. You need to check your database for the types of the fields. I had to guess. Each parameters value is set except sy which changes on each iteration.
No need to close the connection after the last Select command since the final End Using will close and dispose.
After the connection is closed we update the user interface.
Private Sub OPCode(variable1 As String, variable2 As String, variable3 As String, variable4 As String, variable5 As String)
Dim dtBeforeUpdate As New DataTable()
Dim dtAfterUpdate As New DataTable()
Using mysqlconn = New MySqlConnection("server=localhost;user id=root;password=1234;database=Share")
Using cmd As New MySqlCommand("SELECT Column4_Name FROM name_list;", mysqlconn)
mysqlconn.Open()
dtBeforeUpdate.Load(cmd.ExecuteReader)
mysqlconn.Close()
End Using
Using cmd As New MySqlCommand($"UPDATE Name_list Set Numerology = #Numerologh, FSTLetter = #FST, Timing = #Timing, P_Numerology = #P_Numerology WHERE Symbol = #sy ", mysqlconn)
cmd.Parameters.Add("#Numerology", MySqlDbType.String).Value = $"N-{variable1} S- {variable2}"
cmd.Parameters.Add("#FST", MySqlDbType.String).Value = variable3
cmd.Parameters.Add("#Timing", MySqlDbType.String).Value = variable4
cmd.Parameters.Add("#P_Numerology", MySqlDbType.String).Value = variable5
cmd.Parameters.Add("#sy", MySqlDbType.String)
mysqlconn.Open()
For Each row As DataRow In dtBeforeUpdate.Rows
cmd.Parameters("#sy").Value = row(0).ToString.Trim
cmd.ExecuteNonQuery()
Next
mysqlconn.Close()
End Using
Using cmd As New MySqlCommand("Select * From Name_list;", mysqlconn)
mysqlconn.Open()
dtAfterUpdate.Load(cmd.ExecuteReader)
End Using
End Using
DataGridView1.DataSource = dtAfterUpdate
End Sub
Actually, I don't get it. It seems like you are updated the entire table with the same data. Do you expect the variable1, variable2 etc. to change somehow?
Don't know where your variable1, variable2, etc come from, but those look to be static, so your loop is somewhat pointless it would seem. You're updating every row in the loop to the exact same values (unless there's other code you're not showing), so just update the table without the loop:
Using con As New MySQLConnection
con.ConnectionString = "server=localhost;user id=root;password=1234;database=Share"
con.Open
Using cmd As New MySQLCommand
cmd.Connection = con
cmd.CommandText = "UPDATE Name_list Set Numerology = '" & "N-" & variable1 & " S- " & variable2 & "',FSTLetter = '" & variable3 & "',Timing = '" & vriable4 & "',P_Numerology = '" & variable5 & "'"
cmd.ExecuteNonQuery
End Using
End Using
Im trying to edit items after inserting to access by clicking the save button? How can i save the edits done in datagridview rows to access?
Already tried the update query
For each loop
vb.net
Private Sub BunifuFlatButton1_Click(sender As Object, e As EventArgs) Handles BunifuFlatButton1.Click
Dim constring As String = ("Provider=Microsoft.ACE.OLEDB.12.0;Data Source= C:\Users\PU-IMO\Desktop\BlueWavesIS - Copy\BlueWavesIS\BlueWavesIS.accdb")
Dim conn As New OleDbConnection(constring)
For Each row As DataGridViewRow In DataGridView1.Rows
Using con As New OleDbConnection(constring)
'nettxt.Text = (grosstxt.Text * perdistxt.Text / 100) - (dislctxt.Text + disusd.Text + distax.Text)
Dim cmd As New OleDbCommand("Update PurchaseInvoice set [Itemnum] = #ItemNum, [Itemname]= #ItemName, [Itemqty]= #ItemQty, [Itemprice] = #ItemPrice, [discount] =#discount, [subtotal] = #subtotal,[Preference] = " & preftxt.Text & ", [Suppnum] = " & pnumtxt.Text & ", [UniqueID] = " & pautotxt.Text & " Where [UniqueID] = " & pautotxt.Text & "", con)
cmd.Parameters.AddWithValue("#ItemID", row.Cells("ItemID").Value)
cmd.Parameters.AddWithValue("#ItemName", row.Cells("ItemName").Value)
cmd.Parameters.AddWithValue("#ItemQty", row.Cells("ItemQty").Value)
cmd.Parameters.AddWithValue("#ItemPrice", row.Cells("ItemPrice").Value)
cmd.Parameters.AddWithValue("#discount", row.Cells("discount").Value)
cmd.Parameters.AddWithValue("#subtotal", row.Cells("subtotal").Value)
cmd.Parameters.AddWithValue("#Ref", preftxt.Text.ToString)
cmd.Parameters.AddWithValue("#Suppnum", Convert.ToInt32(pnumtxt.Text))
cmd.Parameters.AddWithValue("#UniqueID", Convert.ToInt32(pautotxt.Text))
DataGridView1.AllowUserToAddRows = False
con.Open()
cmd.ExecuteNonQuery()
con.Close()
End Using
Next
'This the code i used to show the data in datagridview:
Private Sub NewPurchaseInvoice_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim con As New OleDbConnection
con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source= C:\Users\PU-IMO\Desktop\BlueWavesIS - Copy\BlueWavesIS\BlueWavesIS.accdb"
con.Open()
Dim sql As String = "Select [Itemnum],[Itemname],[Itemprice],[ItemQty],[discount],[subtotal] from PurchaseInvoice where [UniqueID] = " & pautotxt.Text & ""
Dim cmd10 As OleDbCommand = New OleDbCommand(Sql, con)
'Dim adap As New OleDbDataAdapter("Select [Itemnum],[Itemname],[Itemprice],[discount],[subtotal] from PurchaseInvoice where UniqueID = " & pautotxt.Text & "", con)
'Dim ds As New System.Data.DataSet
'adap.Fill(ds, "PurchaseInvoice")
Dim dr As OleDbDataReader = cmd10.ExecuteReader
Do While dr.Read()
DataGridView1.Rows.Add(dr("ItemNum"), dr("ItemName"), dr("ItemQty"), dr("ItemPrice"), dr("discount"), dr("subtotal"))
Loop
con.Close()
I expect that all the rows will be updated as each other, but the actual output is that each row has different qty name etc...
This code does not seem appropriate in the load event because pautotxt.Text will not have a value yet. Can you move it to a Button.Click?
I guessed that the datatype of ID is an Integer. You must first test if the the .Text property can be converted to an Integer. .TryParse does this. It returns a Boolean and fills IntID that was provided as the second parameter.
You can pass the connection string directly to the constructor of the connection. The Using...End Using blocks ensure that your database objects are closed and disposed even if there is an error. You can pass the Select statement and the connection directly to the constructor of the command.
ALWAYS use Parameters, never concatenate strings to avoid sql injection. Don't use .AddWithValue. See http://www.dbdelta.com/addwithvalue-is-evil/
and
https://blogs.msmvps.com/jcoehoorn/blog/2014/05/12/can-we-stop-using-addwithvalue-already/
and another one:
https://dba.stackexchange.com/questions/195937/addwithvalue-performance-and-plan-cache-implications
The DataAdapter will open the connection, fiil the DataTable and close the connection if it finds it closed; however if it is found open it will leave it open.
The last line binds the grid to the DataTable.
Private Sub FillGrid()
If Not Integer.TryParse(pautotxt.Text, IntID) Then
MessageBox.Show("Please enter a number")
Return
End If
dt = New DataTable()
Using con As New OleDbConnection(ConnString)
Using cmd As New OleDbCommand(Sql, con)
cmd.Parameters.Add("#ID", OleDbType.Integer).Value = IntID
Dim adap = New OleDbDataAdapter(cmd)
adap.Fill(dt)
End Using
End Using
DataGridView1.DataSource = dt
End Sub
DataTables are very clever. When bound to a DataGridView they keep track of changes and mark rows as update, insert, or delete. The DataAdapter uses this info to update the database. Once the database is updated we call .AcceptChanges on the DataTable to clear the marking on the rows.
Private Sub UpdateDatabase()
Using cn As New OleDbConnection(ConnString)
Using da As New OleDbDataAdapter(Sql, cn)
da.SelectCommand.Parameters.Add("#ID", OleDbType.Integer).Value = IntID
Using builder As New OleDbCommandBuilder(da)
da.Update(dt)
End Using
End Using
End Using
dt.AcceptChanges()
End Sub
I can select the data from an Access database, but I tried many ways to INSERT INTO database. There is no error message, but it didn't insert the data.
Code:
Dim conn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & CurDir() & "\fsDB1.accdb")
Dim cmd As OleDbCommand
Dim dr As OleDbDataReader
conn.Open()
Dim CommandString As String = "INSERT INTO tblfile(stdUname,filePw,filePath,status) VALUES('" & userName & "','" & filePw & "','" & filePath & "','A')"
Dim command As New OleDbCommand(CommandString, conn)
Command.Connection = conn
Command.ExecuteNonQuery()
I just want a simple easy way to INSERT INTO an Access database. Is it possible because of the problem of Access database? I can insert this query by running query directly in Access.
Firstly I would check the database settings. If your app copies a new copy of the database each time you run it that would explain why you can select existing data and why your new data is not being saved (Well it is being saved, but the database keeps getting replaced with the old one). Rather set it up to COPY IF NEWER.
Further, you should ALWAYS use parameterized queries to protect your data. It is also is less error prone than string concatenated commands ans is much easier to debug.
Also, I recommend using a USING block to handle database connections so that your code automatically disposes of resources no longer needed, just in case you forget to dispose of your connection when you are done. Here is an example:
Using con As New OleDbConnection
con.ConnectionString = "Provider = Microsoft.ACE.OLEDB.12.0; " & _
"Data Source = "
Dim sql_insert As String = "INSERT INTO Tbl (Code) " & _
"VALUES " & _
"(#code);"
Dim sql_insert_entry As New OleDbCommand
con.Open()
With sql_insert_entry
.Parameters.AddWithValue("#code", txtCode.Text)
.CommandText = sql_insert
.Connection = con
.ExecuteNonQuery()
End With
con.Close()
End Using
Here is an example where data operations are in a separate class from form code.
Calling from a form
Dim ops As New Operations1
Dim newIdentifier As Integer = 0
If ops.AddNewRow("O'brien and company", "Jim O'brien", newIdentifier) Then
MessageBox.Show($"New Id for Jim {newIdentifier}")
End If
Back-end class where the new primary key is set for the last argument to AddNewRow which can be used if AddNewRow returns true.
Public Class Operations1
Private Builder As New OleDbConnectionStringBuilder With
{
.Provider = "Microsoft.ACE.OLEDB.12.0",
.DataSource = IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Database1.accdb")
}
Public Function AddNewRow(
ByVal CompanyName As String,
ByVal ContactName As String,
ByRef Identfier As Integer) As Boolean
Dim Success As Boolean = True
Dim Affected As Integer = 0
Try
Using cn As New OleDbConnection With {.ConnectionString = Builder.ConnectionString}
Using cmd As New OleDbCommand With {.Connection = cn}
cmd.CommandText = "INSERT INTO Customer (CompanyName,ContactName) VALUES (#CompanyName, #ContactName)"
cmd.Parameters.AddWithValue("#CompanyName", CompanyName)
cmd.Parameters.AddWithValue("#ContactName", ContactName)
cn.Open()
Affected = cmd.ExecuteNonQuery()
If Affected = 1 Then
cmd.CommandText = "Select ##Identity"
Identfier = CInt(cmd.ExecuteScalar)
Success = True
End If
End Using
End Using
Catch ex As Exception
Success = False
End Try
Return Success
End Function
End Class
I am working with a local .mdf file and I execute some queries to the database and I am using USING blocks to make sure the SqlConnection and SqlReader are disposed of correctly.
I then try to read the data of the file to generate a MD5 Hash of the file but it says the file is still in use.
The code isn't the cleanest it is my first time working with the Sql in a VB.NET app.
SQL Insert:
Dim finalW As String = ""
Dim finalO() As String
Dim currentcounter As Integer = 0
For Each Dir As String In System.IO.Directory.GetDirectories(Pathfinder)
Dim dirInfo As New System.IO.DirectoryInfo(Dir)
Dim temp As New List(Of String)
For Each currentFile In Directory.GetFiles(Pathfinder & "\" & dirInfo.Name & "\", "*.png", SearchOption.TopDirectoryOnly)
temp.Add(Path.GetFileName(currentFile))
Next
If temp.Count <> 0 Then
finalW = temp.Find(AddressOf GetNewIcon)
finalO = temp.FindAll(AddressOf GetOldIcon).ToArray
If finalW <> "" Then
Using con As New SqlClient.SqlConnection("Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=""" & PathFinal & "ImaginiDB.mdf"";Integrated Security=True")
con.Open()
Using cmd = con.CreateCommand()
cmd.CommandType = CommandType.Text
cmd.CommandText = "INSERT NewIcon (Name) VALUES ('" & finalW.Trim() & "')"
cmd.Connection = con
cmd.ExecuteNonQuery()
End Using
currentcounter = currentcounter + 1
Dim Id As String = ""
Using command = con.CreateCommand()
command.CommandType = CommandType.Text
command.CommandText = "SELECT * FROM NewIcon WHERE Name='" & finalW & "'"
Using reader As SqlDataReader = command.ExecuteReader()
While reader.Read()
Id = reader(0)
End While
End Using
End Using
For Each item As String In finalO
Using cmd2 = con.CreateCommand()
cmd2.CommandType = CommandType.Text
cmd2.CommandText = "INSERT OldIcon (NID,Name) VALUES ('" & Id & "','" & item.ToString.Trim() & "')"
cmd2.Connection = con
cmd2.ExecuteNonQuery()
End Using
currentcounter = currentcounter + 1
Next
Dim cur As Long = currentcounter * 100 / counter
SetProgress(cur)
End Using
End If
End If
Next
GC.Collect()
GC.WaitForPendingFinalizers()
SetLabel4Text("FINISHED IMPORT", Color.Red)
MD5 Generation ran after this process is finished:
Public Function GenMD5(ByVal Filename As String) As String
Dim MD5 = System.Security.Cryptography.MD5.Create
Dim Hash As Byte()
Dim sb As New System.Text.StringBuilder
Using st As New IO.FileStream(Filename, IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.Read)
Hash = MD5.ComputeHash(st)
End Using
For Each b In Hash
sb.Append(b.ToString("X2"))
Next
Return sb.ToString
End Function
So as mentioned in the comment by #jmcilhinney
Different connections use different pool as the MSDN says:
When a connection is first opened, a connection pool is created based
on an exact matching algorithm that associates the pool with the
connection string in the connection.
Thus I decided to implement the method:
SqlConnection.ClearPool(connection As SqlConnection)
I placed this just before my END USING:
Dim cur As Long = currentcounter * 100 / counter
SetProgress(cur)
SqlConnection.ClearPool(con)
End Using
Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
Dim READER As MySqlDataReader
Dim Query As String
Dim connection As MySqlConnection
Dim COMMAND As MySqlCommand
Dim item As Object
Try
item = InputBox("What is the item?", "InputBox Test", "Type the item here.")
If item = "shoe" Then
Dim connStr As String = ""
Dim connection As New MySqlConnection(connStr)
connection.Open()
Query = "select * from table where username= '" & Login.txtusername.Text & " '"
COMMAND = New MySqlCommand(Query, connection)
READER = COMMAND.ExecuteReader
If (READER.Read() = True) Then
Query = "UPDATE table set noOfItems = noOfItems+1, week1 = 'found' where username= '" & Login.txtusername.Text & "'"
Dim noOfItems As Integer
Dim username As String
noOfItems = READER("noOfItems") + 1
username = READER("username")
MessageBox.Show(username & "- The number of items you now have is: " & noOfGeocaches)
End If
Else
MsgBox("Unlucky, Incorrect item. Please see hints. Your score still remains the same")
End If
Catch ex As Exception
MessageBox.Show("Error")
End Try
I finally got the message box to display! but now my code does not increment in the database, can anybody help me please :D
Thanks in advance
After fixing your typos (space after the login textbox and name of the field retrieved) you are still missing to execute the sql text that updates the database.
Your code could be simplified understanding that an UPDATE query has no effect if the WHERE condition doesn't find anything to update. Moreover keeping an MySqlDataReader open while you try to execute a MySqlCommand will trigger an error in MySql NET connector. (Not possible to use a connection in use by a datareader). We could try to execute both statements in a single call to ExecuteReader separating each command with a semicolon and, of course, using a parameter and not a string concatenation
' Prepare the string for both commands to execute
Query = "UPDATE table set noOfItems = noOfItems+1, " & _
"week1 = 'found' where username= #name; " & _
"SELECT noOfItems FROM table WHERE username = #name"
' You already know the username, don't you?
Dim username = Login.txtusername.Text
' Create the connection and the command inside a using block to
' facilitate closing and disposing of these objects.. exceptions included
Using connection = New MySqlConnection(connStr)
Using COMMAND = New MySqlCommand(Query, connection)
connection.Open()
' Set the parameter value required by both commands.
COMMAND.Parameters.Add("#name", MySqlDbType.VarChar).Value = username
' Again create the reader in a using block
Using READER = COMMAND.ExecuteReader
If READER.Read() Then
Dim noOfItems As Integer
noOfItems = READER("noOfItems")
MessageBox.Show(username & "- The number of items you now have is: " & noOfItems )
End If
End Using
End Using
End Using