I beg the idea to handle query data with better speed. Already tried using, index or Store Procedures, but still often do not get the value of the data (the data some time empty).
Table (tbl_Phonebook) contains thousands of data that contains the phone number and name of the owner of the phone.
Thank You
This is MyCode:
Private Sub FrmLogger_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Timer1.Interval = 50
Timer1.Enabled = True
End Sub
Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
'check data (phonenumber) in ChannelData
For i = 0 To 31 'length of objChannelData
If objChannelData(i) <> "" Then
DataGridView1.Rows(i).Cells.Item(1).Value() = objChannelData(i) 'the value is PhoneNumber
DataGridView1.Rows(i).Cells.Item(2).Value() = GetPhoneBookName(objChannelData(i)) ' try to get Name of PhoneNumber owner
End If
Next
End Sub
Private Function GetPhoneBookName(ByVal nPhoneNumber As String) As String
'check db connection
Try
If (Conn_MySQL.State = ConnectionState.Closed) Then
Conn_MySQL.Open()
End If
'get value from table
Dim strSQL As String = "select fPhoneName from tbl_Phonebook where fPhoneNumber = '" & nPhoneNumber & "'"
Dim myCommand As New MySqlCommand(strSQL, Conn_MySQL)
Dim myReader As MySqlDataReader
myReader = myCommand.ExecuteReader()
myReader.Read()
If myReader.HasRows Then
If Not IsDBNull(myReader.GetValue(0)) Then
Return myReader.GetString(0)
Else
Return ""
End If
myReader.Close()
Else
Return ""
End If
Catch ex As Exception
Return ""
End Try
End Function
Related
I want to know how the system recognize if the question is already answered or not if the user want to go back in previous question. if its already answered the answer will update either the score is increase or not or if the answer is not edited it will be the same.
BUTTON1 is to go back to previous quesion
Button2 is for checking if true or false the answwer
BUTTON 3 is for Keep going the exam
Here are my code snippets:
Imports MySql.Data.MySqlClient
Imports System.Drawing
Imports System.IO
Public Class Exam
'declaring variables for connection'
Dim score As Integer
Dim rightans As String
Dim correct As Integer = 0
Dim choice As String
Dim choice1 As String
Dim choice2 As String
Dim choice3 As String
Dim con As MySqlConnection
Dim con1 As MySqlConnection
Dim COMMAND As MySqlCommand
Dim read As MySqlDataReader
Dim da As MySqlDataAdapter
Dim sql As String
Private Sub Exam_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'setting the radiobutton to false, so that when the form load there is no shaded button'
Label2.Text = 1
A.Checked = False
B.Checked = False
C.Checked = False
D.Checked = False
con = New MySqlConnection
Button1.Enabled = False
con.ConnectionString = "server=localhost;userid=root;password=;database=user;"
'calling sub
qno()
End Sub
Sub clear()
'to set the radiobutton false/no shaded.
A.Checked = False
B.Checked = False
C.Checked = False
D.Checked = False
End Sub
Sub qno()
'calling connection'
Try
con = New MySqlConnection
con.ConnectionString = "server=localhost; user id=root; password=; database=user;"
con.Open()
sql = "SELECT * FROM user.math WHERE question_id = #ID;"
COMMAND = New MySqlCommand
With COMMAND
.Connection = con
.CommandText = sql
.Parameters.Clear()
.Parameters.AddWithValue("#ID", Label2.Text)
.ExecuteNonQuery()
End With
Dim arrImage() As Byte
Dim dt As New DataTable
da = New MySqlDataAdapter
da.SelectCommand = COMMAND
da.Fill(dt)
If dt.Rows.Count > 0 Then
arrImage = dt.Rows(0).Item(7)
Dim mstream As New System.IO.MemoryStream(arrImage)
Pic1.Image = Image.FromStream(mstream)
question.Text = dt.Rows(0).Item(1)
A.Text = dt.Rows(0).Item(2)
B.Text = dt.Rows(0).Item(3)
C.Text = dt.Rows(0).Item(4)
D.Text = dt.Rows(0).Item(5)
Else
MsgBox("No results!")
End If
Catch ex As MySqlException
MsgBox(ex.Message)
Finally
con.Close()
da.Dispose()
End Try
End Sub
Sub increment()
'incrementing the score f the answer is correct'
Dim i As Integer = 0
i = Label2.Text
i = i + 1
Label2.Text = i
If Label2.Text > 1 Then
Button1.Enabled = True
End If
End Sub
Sub decrement()
'incrementing the score f the answer is correct'
Dim i As Integer = 1
i = Label2.Text
i = i - 1
Label2.Text = i
If Label2.Text = 1 Then
Button1.Enabled = False
End If
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
'checking of the user answer the questions'
If ((A.Checked = False) And (B.Checked = False) And (C.Checked = False) And (D.Checked = False)) Then
MsgBox("Please answer the question")
Else
'if the examinee answers all the examination it will call another questions from database'
If A.Checked = True Then
con.Open()
' Dim ans As String
Dim arren As String = "A"
Dim sql As String = ("select answer from user.math where question_id = '" & Label2.Text & "' ")
COMMAND = New MySqlCommand(sql, con)
Dim it As String
read = COMMAND.ExecuteReader
If read.HasRows Then
If read.Read Then
it = read.Item("answer")
If it = choice Then
correct = correct + 1
Label4.Text = correct
ElseIf it <> choice And Label2.Text <= 1 Then
correct = correct - 1
Label4.Text = correct
End If
End If
clear()
End If
If Label2.Text = 10 Then
MessageBox.Show("proceed to other subject test")
End If
con.Close()
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
decrement()
qno()
End Sub
End Class
Untested since I don't have your database. Comments above and inline.
Public Class Form3
Dim correct As Integer = 0
Private Sub Exam_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'setting the radiobutton to false, so that when the form load there is no shaded button'
Label2.Text = "1"
A.Checked = False
B.Checked = False
C.Checked = False
D.Checked = False
Button1.Enabled = False
qno()
End Sub
Private Sub clear()
'to set the radiobutton false/no shaded.
A.Checked = False
B.Checked = False
C.Checked = False
D.Checked = False
End Sub
Private Sub qno()
Try
'Using...End Using blocks will close and dispose of your objects
Using con = New MySqlConnection("server=localhost;userid=root;password=;database=user;")
Using Cmd = New MySqlCommand("SELECT * FROM user.math WHERE question_id = #ID;", con)
Cmd.Parameters.AddWithValue("#ID", Label2.Text)
Dim arrImage() As Byte
Dim dt As New DataTable
Using da = New MySqlDataAdapter
da.SelectCommand = Cmd
da.Fill(dt)
If dt.Rows.Count > 0 Then
'Not at all sure about this picture code
arrImage = CType(dt.Rows(0).Item(7), Byte())
Dim mstream As New System.IO.MemoryStream(arrImage)
Pic1.Image = Image.FromStream(mstream)
question.Text = dt.Rows(0).Item(1).ToString
A.Text = dt.Rows(0).Item(2).ToString
B.Text = dt.Rows(0).Item(3).ToString
C.Text = dt.Rows(0).Item(4).ToString
D.Text = dt.Rows(0).Item(5).ToString
'guessing that answer it item 6
HiddenLabel.Text = dt.Rows(0).Item(6).ToString
Else
MsgBox("No results!")
End If
End Using
End Using
End Using
Catch ex As MySqlException
MsgBox(ex.Message)
End Try
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
'checking of the user answer the questions'
If ((A.Checked = False) And (B.Checked = False) And (C.Checked = False) And (D.Checked = False)) Then
MsgBox("Please answer the question")
Exit Sub
End If
'The correct answer was put in the HiddenLabel.Text (Visible set to False)
'in the qno Sub
Dim CorrectAnswer As String = HiddenLabel.Text
Dim UserChoice As String = ""
If A.Checked Then
UserChoice = "A"
ElseIf B.Checked Then
UserChoice = "B"
ElseIf C.Checked Then
UserChoice = "C"
Else
UserChoice = "D"
End If
If UserChoice = CorrectAnswer Then
correct += 1
Else
'It is very hard to get a good score if it is decremented with every wrong answer
'Why not skip this and just give a zero for a wrong answer
correct -= 1
End If
Label4.Text = correct.ToString
clear()
If Label2.Text = "10" Then
MessageBox.Show("proceed to other subject test")
Me.Hide()
exam2.Show()
Else
'Add code to keep track of question number in
'Add code to show the next question
End If
End Sub
Hello Everyone Good Afternoon,
I have an Object in a form and they are Datagridview1 and a Save Button the Datagridview1 will populate data from my Database on Form_Load and the Data will show with a Corresponding Checkbox. Like the Image below
and If you here is the code for that
Private Sub loadtech()
Dim con1 As MySqlConnection = New MySqlConnection("datasource=localhost;database=operations;userid=root;password=admin1950;Convert Zero Datetime=True")
Dim sql1 As MySqlCommand = New MySqlCommand("select TechName from technicians order by Category ASC", con1)
Dim ds1 As DataSet = New DataSet
Dim adapter1 As MySqlDataAdapter = New MySqlDataAdapter
con1.Open()
adapter1.SelectCommand = sql1
adapter1.Fill(ds1, "MyTable")
DataGridView1.DataSource = ds1.Tables(0)
con1.Close()
With DataGridView1
.RowHeadersVisible = False
.Columns(0).HeaderCell.Value = "Technician / Electrician"
End With
DataGridView1.Columns.Item(0).Width = 150
DataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.BottomCenter
Me.DataGridView1.DefaultCellStyle.WrapMode = DataGridViewTriState.True
Me.DataGridView1.Columns(0).DefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleLeft
Dim checkBoxColumn As New DataGridViewCheckBoxColumn()
checkBoxColumn.HeaderText = "Tag"
checkBoxColumn.Width = 30
checkBoxColumn.Name = "checkBoxColumn"
DataGridView1.Columns.Insert(0, checkBoxColumn)
End Sub
and my Question is how can I save the Checked Row in Database? Lets say I checked all of it so the Rows will be saved in Database. (Regardless of How many I Checked)
Here is my code but its not working. :(
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim conn As MySqlConnection = New MySqlConnection("datasource=localhost;database=operations;userid=root;password=admin1950;Convert Zero Datetime=True")
conn.Open()
Dim comm As MySqlCommand = New MySqlCommand()
comm.Connection = conn
Dim name As String
For i As Integer = 0 To Me.DataGridView1.Rows.Count
name = Me.DataGridView1.Rows(0).Cells(1).Value
comm.CommandText = "insert into assignments(ElecAssigned) values('" & name & "')"
comm.ExecuteNonQuery()
Next
conn.Close()
End Sub
TYSM For future help
Yes, your loop is slightly incorrect. Try using this loop and see if that fixes your issue. The issue, you didn't use the i variable. It should be placed in Row(i) and you were looping from 0 to Count when it should be 0 to Count - 1
Dim name As String
For i As Integer = 0 To Me.DataGridView1.Rows.Count - 1 Step 1
If Me.DataGridView1.Rows(i).Cells(0).Value = True Then
name = Me.DataGridView1.Rows(i).Cells(1).Value
comm.CommandText = "insert into assignments(ElecAssigned) values('" & name & "')"
comm.ExecuteNonQuery()
End If
Next
I have problem when i'm trying to fetch data from mysql database
I always get the last record.
How can I get all records showing on the datagridview synchronously
Here is my code
Please can someone help me
Public Class Form1
Private RowCount As Integer = 0
Private Sub bgw_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
ListBox1.Items.Add(e.UserState)
ProgressBar1.Value = e.ProgressPercentage
Label1.Text = "Processing row.. " + e.ProgressPercentage.ToString()
DataGridView1.Rows.Add(New Object() {f1, f2})
Me.ProgressBar1.Maximum = RowCount
End Sub
Dim ListText As String
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles go.Click
go.Enabled = False
cancel.Enabled = True
ListBox1.Items.Clear()
ProgressBar1.Value = 0
BackgroundWorker1.WorkerReportsProgress = True
BackgroundWorker1.WorkerSupportsCancellation = True
BackgroundWorker1.RunWorkerAsync()
Me.Cursor = Cursors.WaitCursor
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cancel.Click
BackgroundWorker1.CancelAsync()
End Sub
Private Sub bgw_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
go.Enabled = True
cancel.Enabled = False
Me.Cursor = Cursors.Arrow
DataGridView1.Refresh()
DataGridView1.CurrentCell = DataGridView1(0, DataGridView1.Rows.Count - 1)
End Sub
Dim f1 As String
Dim f2 As String
Dim ds As New DataSet
Dim command As MySqlCommand
Dim reader As MySqlDataReader
Private Sub BackgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
GetRecordCount()
Dim connetionString As String
Dim connection As MySqlConnection
Dim i As Integer = 0
Dim sql As String
connetionString = "Server=db4free.net;User Id=mouhcindinaoui;Password=$$$$$$;Database=mouhcindinaoui"
sql = "SELECT id,nom FROM dep02 "
connection = New MySqlConnection(connetionString)
Try
connection.Open()
command = New MySqlCommand(sql, connection)
reader = command.ExecuteReader()
For Value As Integer = 0 To rowcount
If reader.HasRows Then
Do While reader.Read()
f1 = reader.GetString("id")
f2 = reader.GetString("nom")
Loop
End If
ListText = String.Concat("Sequence #", Value)
BackgroundWorker1.ReportProgress(Value, ListText)
Thread.Sleep(10)
Next
reader.Close()
command.Dispose()
connection.Close()
Catch ex As Exception
' MsgBox("Can not open connection ! ")
End Try
End Sub
Private Sub GetRecordCount()
Dim connetionString As String
Dim connection As MySqlConnection
Dim command As MySqlCommand
Dim sql As String
connetionString = "Server=db4free.net;User Id=mouhcindinaoui;Password=dinaouimouhcin1991;Database=mouhcindinaoui"
sql = "Select count(*) from dep02"
connection = New MySqlConnection(connetionString)
command = New MySqlCommand(sql, connection)
connection.Open()
RowCount = CInt(command.ExecuteScalar())
End Sub
End Class
You are calling ReportProgress only at the end of the loop on the DataReader. Of course, at that point the two variables f1 and f2 used to set items in your grid contain the value of the last record read by the DataReader.
You need to move the call inside the DataReader loop
For Value As Integer = 0 To rowcount
If reader.HasRows Then
Do While reader.Read()
f1 = reader.GetString("id")
f2 = reader.GetString("nom")
ListText = String.Concat("Sequence #", Value)
BackgroundWorker1.ReportProgress(Value, ListText)
Loop
End If
Thread.Sleep(10)
Next
However it is totally useless the call to GetRecordCount and the external loop on the rowcount variable (and plain wrong). The while loop on the DataReader doesn't need it and your could remove all of it replacing everything with a simple increment of a local variable to keep the progressive of the current record inside the datareader loop
Dim recNum = 1
If reader.HasRows Then
Do While reader.Read()
f1 = reader.GetString("id")
f2 = reader.GetString("nom")
ListText = String.Concat("Sequence #", recNum)
BackgroundWorker1.ReportProgress(Value, ListText)
recNum = recNum + 1
Loop
End If
Can anyone help me on this? What I wanted to happen is that if the value exist in Table 1 (employee), it will then check Table 2 (mobilelist) if it also exist there. Here's the code:
Private Sub TextBox_IDNumber_LostFocus(sender As Object, e As EventArgs) Handles TextBox_IDNumber.LostFocus
Mysqlconn = New MySqlConnection
Mysqlconn.ConnectionString = "server=localhost;userid=root;password=12345;database=my_db"
Dim READER As MySqlDataReader
Dim READER2 As MySqlDataReader
Dim _isFound As Boolean = False
Dim _isExist As Boolean = False
Try
Mysqlconn.Open()
Dim empmr As String
Dim empml As String
Dim fn1 As String
Dim fn2 As String
Dim ln1 As String
Dim ln2 As String
empmr = "Select * from my_db.employee where IDNumber ='" & TextBox_IDNumber.Text & "'"
empml = "Select * from my_db.mobilelist where IDNumber = '" & TextBox_IDNumber.Text & "' AND DateAssigned is not Null AND DateReturned is Null"
Command = New MySqlCommand(empmr, Mysqlconn)
READER = Command.ExecuteReader
While READER.Read()
_isFound = True
fn1 = READER.GetString("FirstName")
ln1 = READER.GetString("LastName")
End While
If _isFound Then
TextBox_FirstName.Text = fn1
TextBox_LastName.Text = ln1
ElseIf Not _isExist Then
MessageBox.Show("Record Not Found in Master Data")
TextBox_IDNumber.Clear()
TextBox_FirstName.Clear()
TextBox_LastName.Clear()
TextBox_IDNumber.Focus()
End If
Catch ex As MySqlException
MessageBox.Show("Error!")
Finally
Mysqlconn.Dispose()
End Try
End Sub
Assuming you have the appropriate Primary Key and Foreign Key relationship between the tables Employee and MobileList you use this query to find records on the MobileList table for an employee:
Dim myQuery as string
myQuery = "SELECT FirstName, LastName, MobileNumber
FROM Employee
JOIN MobileList
ON Employee.IDNumber=MobileList.IDNumber
WHERE Employee.IDNumber=#ID"
Note: You should rename the IDNumber column on the MobileList to avoid confusion.
You should also improve your access to the database with the Using statement and take advantage of Parameters to prevent SQL injection:
Using myConn As New SqlConnection("Your connection string")
myConn.Open()
Using myCmd As New SqlCommand(myQuery, myConn)
myCmd.Parameters.AddWithValue("#ID", "Your ID value")
Using myReader As SqlDataReader = myCmd.ExecuteReader()
If myReader.HasRows Then
'There are mobile numbers issued to that ID'
Do While myReader.Read()
'Iterate through all existing records'
Loop
Else
'There are no mobile numbers issued to that ID'
End If
End Using
End Using
End Using
Keep in mind that this gives you the mobile numbers for a particular employee, it doesn't tell you if a particular employee exists.
I have a Datagridview and I want to delete a row in my MySQL database.
I have some code but I get an error, it says ID is null. My ID is a string which is the value of the ID where the columns are checked. My first column "column 0" is a checkbox column
Here is the code:
Feel free to ask specific questions if you don't understand what I am asking.
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim RowsToDelete As New List(Of DataGridViewRow)
Try
For Each row As DataGridViewRow In DataGridView1.Rows
If row.Cells(0).Value = True Then
DeleteRow(row.Cells(1).Value)
RowsToDelete.Add(row)
End If
Next
Catch ex As Exception
MessageBox.Show(ex.ToString)
End Try
For Each rowtodelete In RowsToDelete
DataGridView1.Rows.Remove(rowtodelete)
next
End Sub
Private Sub DeleteRow(ByVal ID As Integer)
Dim MySQLCon As New MySqlConnection
Dim ConnectionString As String = "server=localhost;user id=root;password=;database=business elements"
MySQLCon.ConnectionString = ConnectionString
Dim CMD As MySqlCommand
MySQLCon.Open()
Try
CMD.Connection = MySQLCon
CMD.CommandText = "DELETE FROM `users` WHERE `ID` = " & ID
Catch ex As Exception
End Try
MySQLCon.Close()
MySQLCon.Dispose()
End Sub
Without seeing all of your code, something like this should work:
Dim sql as String
sql = "DELETE FROM `users` WHERE `ID` IN ("
For Each row As DataGridViewRow In DataGridView1.Rows
If row.Cells(0).Value = True Then
ID = row.Cells(1).Value
DeleteRow(row.Cells(1).Value)
RowsToDelete.Add(row)
sql += ID + ","
End If
Next
If sql.Left(sql.Length-1) = "," Then
CMD.CommandText = sql.Left(sql.Length-1) + ")"
CMD.Connection = MySQLCon
CMD.ExecuteNonQuery()
End If
Good luck.
Finally found the code:
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Dim RowsToDelete As New List(Of DataGridViewRow)
Try
For Each row As DataGridViewRow In DataGridView1.Rows
If row.Cells(0).Value = True Then
DeleteRow(row.Cells(1).Value)
RowsToDelete.Add(row)
End If
Next
Catch ex As Exception
MessageBox.Show(ex.ToString)
End Try
For Each rowtodelete In RowsToDelete
DataGridView1.Rows.Remove(rowtodelete)
Next
End Sub
Private Sub DeleteRow(ByVal ID As Integer)
Dim MySQLCon As New MySqlConnection
Dim ConnectionString As String = "server=localhost;user id=root;password=;database=business elements"
MySQLCon.ConnectionString = ConnectionString
Dim CMD As New MySqlCommand
CMD.CommandText = "DELETE FROM `users` WHERE `ID` = " & ID
MySQLCon.Open()
Try
CMD.Connection = MySQLCon
CMD.ExecuteNonQuery()
Catch ex As Exception
End Try
MySQLCon.Close()
MySQLCon.Dispose()
End Sub
For i As Integer = DataGridView2.Rows.Count - 1 To 0 Step -1
Dim c As Boolean
c = DataGridView2.Rows(i).Cells(0).Value
If c = True Then
=====================================================================================
Dim sql As String = "DELETE FROM Items WHERE ItemID=" & Int(DataGridView2(1, DataGridView2.Rows(i).Index).Value)
' ^^^^^^^^^^^^^^
'
Dim comm As New SqlCommand(sql, con)
con.Open()
Dim result As Integer = comm.ExecuteNonQuery
con.Close()
End If
Next