What I want to achieve is:
I will choose what column should I update, this is why I am experimenting on my code but did not work and now I think I need some help.
Dim btnup="col1"
Dim btnval="1"
Try
Dim mysqlconn As New MySqlConnection
Dim conStr As String
conStr = "Server=localhost; user id=root; password=; database=dnc_floor"
mysqlconn = New MySqlConnection(conStr)
mysqlconn.Open()
Dim update As String
Dim cmd As MySqlCommand
update = "Update floor set ='" & btnup & "'=btnval where ID='" & Day & "'"
cmd = New MySqlCommand(update, mysqlconn)
cmd.ExecuteNonQuery()
Dim check As String = cmd.ExecuteNonQuery()
MsgBox("Saved")
mysqlconn.Close()
Catch ex As MySqlException
MessageBox.Show("Check your connection with your database")
Finally
mysqlconn.Dispose()
End Try
The update string is probably wrong. Maybe u think of that:
update = "Update floor set " & btnup & " ='" & btnval & "' where ID= '" & Day & "'"
Related
Seriously need help. Been figuring this one out for days and I can't seem to get it. Tried all the codes I searched but still no luck.
So here's the problem, for every added existing violation in a student in tablestudentviolation, The numberofviolation will increase from 1st to 2nd to 3rd. How can I do that? I'll post my codes (current in progress codes) and screenshot of the mysql table below for reference
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Mysqlconn = New MySqlConnection
Mysqlconn.ConnectionString =
"server=localhost;uid=root;password=;database=cdm"
Try
Mysqlconn.Open()
Dim query As String
query = "select * from cdm.tablestudentviolations where NameOfViolation = '" & ComboBox1.Text & "' and NumberOfViolation = LAST_INSERT_ID()"
command = New MySqlCommand(query, Mysqlconn)
Dim reader As MySqlDataReader = command.ExecuteReader
If reader.HasRows Then
command = New MySqlCommand(query, Mysqlconn)
reader = command.ExecuteReader
Else
Dim query1 As String
Dim reader1 As MySqlDataReader
Dim command1 As MySqlCommand
query1 = "insert into cdm.tablestudentviolations (StudentNumber,NameOfViolation,Remarks,NumberOfViolation,EmployeeUsername,EmployeeID) values ('" & Studnum.Text & "','" & ComboBox1.Text & "','" & RichTextBox1.Text & "','" & Label2.Text & "', '" & Form5.Label4.Text & "','2')"
command1 = New MySqlCommand(query1, Mysqlconn)
reader1 = command1.ExecuteReader
End If
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Sub
I have no idea how to use parameterized and would like someone to point me into the right direction.
Here's what I'm currently using.
Public Class main
Dim dbCon As New MySqlConnection("Server=localhost;Database=payid;Uid=root")
Dim strQuery As String = ""
Dim SQLCmd As MySqlCommand
Dim DR As MySqlDataReader
Private Sub Use()
Try
strQuery = "UPDATE payid " & _
"SET used='" & amen.Text & "' " & _
"WHERE payid='" & TextBox1.Text & "'"
SQLCmd = New MySqlCommand(strQuery, dbCon)
dbCon.Open()
SQLCmd.ExecuteNonQuery()
dbCon.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
If someone could change that for me I'd be able to do the rest of my code.
strQuery = "UPDATE payid SET used=#used WHERE payid=#payid "
SQLCmd = New MySqlCommand(strQuery, dbCon)
SQLCmd.Parameters.AddWithValue("#used", amen.Text)
SQLCmd.Parameters.AddWithValue("#payid", TextBox1.Text )
Hi stackoverflow people!
I have been recently developing a simple vb.net program that connects to a mysql database to register and login users with given credentials. I have used this code to register my users but I keep getting and error (below the code)
Dim insertUser As String = "INSERT INTO users(ID, username, password, email, verif)" _
& " VALUES('','" & Username.Text & "','" & Password.Text & "','" & Email.Text & "','" & currentRandString & "');"
Dim checkUsername As String = "SELECT * FROM users WHERE username='" & Username.Text & "'"
MysqlConn = New MySqlConnection()
MysqlConn.ConnectionString = mysqlconntxt4reg
MysqlConn.Open()
Dim myCommand As New MySqlCommand
myCommand.Connection = MysqlConn
myCommand.CommandText = checkUsername
myAdapter.SelectCommand = myCommand
Dim myData As MySqlDataReader
myData = myCommand.ExecuteReader
If myData.HasRows > 0 Then
MsgBox("Username Already In Use...", MsgBoxStyle.Critical, "Error")
myData.Close()
Else
myData.Close()
Dim myCommand2 As New MySqlCommand
myCommand2.Connection = MysqlConn
myCommand2.CommandText = insertUser
myAdapter.SelectCommand = myCommand2
Dim myData2 As MySqlDataReader
myData2 = myCommand2.ExecuteReader
Mail(Email.Text, currentRandString)
Me.Close()
myData2.Close()
End If
Catch myerror As MySqlException
MsgBox("Error While Connecting To Database:" & vbNewLine & vbNewLine & myerror.ToString, MsgBoxStyle.Critical, "Error")
Finally
MysqlConn.Dispose()
End Try
I have closed all my datareaders before opening other ones so I do not see why this does not work...
Error:
Link to Error Image
I would appreciate any help on this topic!
Thanks
Rodit
I would use the using statement around all the disposable objects to be sure that they release every references to the connection when they are no more needed, but looking at your code, I think you don't need at all the datareaders because you could resolve your problem just with the commands
Dim insertUser As String = "INSERT INTO users(username, password, email, verif)" _
& " VALUES(#p1, #p2,#p3,#p4)"
Dim checkUsername As String = "SELECT COUNT(*) FROM users WHERE username=#p1"
Using MysqlConn = New MySqlConnection(mysqlconntxt4reg)
Using myCommand = New MySqlCommand(checkUsername, MysqlConn)
MysqlConn.Open()
myCommand.Parameters.AddWithValue("#p1", Username.Text)
Dim result = myCommand.ExecuteScalar()
if result IsNot Nothing AndAlso Convert.ToInt32(result) > 0 Then
MsgBox("Username Already In Use...", MsgBoxStyle.Critical, "Error")
Else
Using myCommand2 = New MySqlCommand(insertUser, MysqlConn)
mycommand2.Parameters.AddWithValue("#p1",Username.Text)
mycommand2.Parameters.AddWithValue("#p2",Password.Text )
mycommand2.Parameters.AddWithValue("#p3",Email.Text)
mycommand2.Parameters.AddWithValue("#p4",currentRandString )
myCommand2.ExecuteNonQuery()
Mail(Email.Text, currentRandString)
End Using
End If
End Using
End Using
Of course I have replaced your string concatenations with a parameterized query. This is really an important thing to do to avoid Sql Injection
I have replaced the query that checks the user existence with a scalar operation that can be used with the command ExecuteScalar. Also, in the first query, it seems that you try to insert the field ID with an empty string. I think that the first field (ID) is an autonumber field and, in this case, you don't add it to the insert query and don't pass any value because the database will calculate that field for you.
When I run this function
For RepeatBooking = 1 To 51
dateConvertedDateToBook = dateDateToBook.Date
dateDateToBook = dateDateToBook.AddDays(7)
strDateToBook = dateConvertedDateToBook.ToString("yyyy-MM-dd")
Try
Dim command As MySqlCommand = New MySqlCommand
Dim sqlQuery As String = "INSERT INTO bookings SET Date=" & "'" & strDateToBook & "',RoomID='" & strComputerRoomToBook & "',Length='" & intNewBookingLength & "',Period='" & intNewStartPeriod & "',UserID='" & intid & "'"
Dim reader As MySqlDataReader
SQLConnection.Open()
command.CommandText = sqlQuery
command.Connection = SQLConnection
reader = command.ExecuteReader
SQLConnection.Close()
Catch excep As Exception
MsgBox(excep.ToString)
End Try
Next
in my program I get an error saying "The connection property has not been set or is null"
How can I get rid of this?
It goes to the exception when it gets to SQLconnection.Open()
I created the ServerString and MySQL connection at the top of the module like so:
Dim ServerString As String = "Server=localhost;User Id=root;Password=**********;Database=rooms"
Dim SQLConnection As MySqlConnection = New MySqlConnection
You are opening a connection without its property
It should be,
Dim SQLConnection As New MySqlConnection(ServerString)
SQLConnection.Open
Also, you may want to use the USING function so that your connection is properly closed.
It seems you are just inserting a bunch of values to your database and not retrieving anything so why do you use a DataReader?
Your code should be something like this:
Using SQLConnection = New MySqlConnection(ServerString)
SQLConnection.Open 'You should open a connection only once
For RepeatBooking = 1 To 51
dateConvertedDateToBook = dateDateToBook.Date
dateDateToBook = dateDateToBook.AddDays(7)
strDateToBook = dateConvertedDateToBook.ToString("yyyy-MM-dd")
Try
Dim sqlQuery As String = "INSERT INTO bookings SET " & _
"Date='" & strDateToBook & "'," & _
"RoomID='" & strComputerRoomToBook & "', " & _
"Length='" & intNewBookingLength & "', " & _
"Period='" & intNewStartPeriod & "', " & _
"UserID='" & intid & "'"
Dim command = New MySqlCommand(sqlQuery, SQLConnection)
command.ExecuteNonQuery
Catch excep As Exception
MsgBox(excep.Message)
End Try
Next
End Using
Also, you may want to change how to pass your values into a parameter. This will prevent SQL Injection.
How to Inserting Label.text data into mySql table.
i have no problem with textbox.text but i can't figure out how it with Label.text
i try the same code with textbox.text
parameterB_Answer.Value = TextBox1.Text
it work find but when i try with
parameterB_Answer.Value = Label1.Text
mySqlReader seems can't read it.
Update:
1.1.1 is label1.text. My Idea is to insert the text "1.1.1" from Label1 as Primary key and the Textbox(textbox1.text) as the following
my code is:
Try
Dim StrSQL As String = "INSERT INTO boranga" & _
"(IdBorangA,Answers)" & _
"VALUES (#B_IdA,#B_Answer);"
Dim myCommand As MySqlCommand = New MySqlCommand(StrSQL, conn.open)
myCommand.CommandType = CommandType.Text
Dim parameterB_IdA As MySqlParameter = New MySqlParameter("#B_IdA", MySqlDbType.VarChar, 300)
parameterB_IdA.Value = Label1.Text
Dim parameterB_Answer As MySqlParameter = New MySqlParameter("#B_Answer", MySqlDbType.VarChar, 300)
parameterB_Answer.Value = TextBox1.Text
With myCommand.Parameters
.Add(parameterB_IdA)
.Add(parameterB_Answer)
End With
Dim result As MySqlDataReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection)
MsgBox("Tersimpan", vbYes, "boranga")
Catch SqlEx As MySqlException
Throw New Exception(SqlEx.Message.ToString())
End Try
but when I change the value of Label1.text (1.1.1) to 111, it works just fine. probably because I put INT for the column for label1.text to fill while "1.1.1" isn't integer
thank a lot
PS:seems i can't post image because low of reputation
Try using this code format first of all:
Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
Dim conn As MySqlConnection
'Connect to the database using these credentials
conn = New MySqlConnection
conn.ConnectionString = "server=your server site (generally long url); user id=login id for mysql user; password=self explanatory; database=name of the DB you're trying to reach"
'Try and connect (conn.open)
Try
conn.Open()
Catch myerror As MySqlException 'If it fails do this... (i.e. no internet connection, etc.)
MsgBox("Error connecting to database. Check your internet connection.", MsgBoxStyle.Critical)
End Try
'MySQL query (where to call for information)
Dim myAdapter As New MySqlDataAdapter
'Tell where to find the file with the emails/passes stored
Dim sqlquery = "SELECT * FROM the database you selected above WHERE Email = '" & txtEmail.Text & "' AND Password = '" & txtPassword.Text & "'"
Dim myCommand As New MySqlCommand
myCommand.Connection = conn
myCommand.CommandText = sqlquery
'Start query
myAdapter.SelectCommand = myCommand
Dim myData As MySqlDataReader
myData = myCommand.ExecuteReader
If myData.HasRows = 0 Then
MsgBox("Invalid email address or password.", MsgBoxStyle.Critical)
Else
MsgBox("Logged in as " & txtEmail.Text & ".", MsgBoxStyle.Information)
Me.Close()
End If
End Sub
And to insert label.text try replacing one of the textbox.text fields first and see if it will accept it. If it does, then the answer was all in the formatting.
Also, do not forget to call:
imports mysql.data.mysqlclient
and make sure to add the mysql.data reference.