Updating MySQL database in xampp using Visual Studio or Visual Basic - mysql

Question

I tried everything that I can do - I'm a beginner at programming. I wanted to update my database in xampp using VB or Visual Studio but can't seem to do it.
This is my code for that form.:
Imports MySql.Data.MySqlClient
Public Class Form4
Public MysqlConn As MySqlConnection
Public cmd As New MySqlCommand
Public da As New MySqlDataAdapter
Public Sub MysqlConnection()
MysqlConn = New MySqlConnection()
'Connection String
MysqlConn.ConnectionString = "server=localhost;" _
& "user id=root;" _
& "password=;" _
& "database=bank"
'OPENING THE MysqlConnNECTION
MysqlConn.Open()
End Sub
Public Sub add()
Dim sql As String
Dim TempTable As New DataTable
sql = "update cbank set Balance = Balance + " & TextBox2.Text & "where AccountID = " & TextBox1.Text & "and PIN = " & TextBox3.Text & ";"
'bind the connection and query
With cmd
.Connection = MysqlConn
.CommandText = sql
End With
da.SelectCommand = cmd
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
MysqlConnection()
add()
End Sub
End Class
There is no error it just that there is no output also

Answer 1

Keep you data objects local so you can be sure they are closed and disposed. A Using...End Using block ensures this even if there is an error. You can make your connection string a form level variable so you can use it anywhere but that is the only form level variable you need.
You can pass your connection string directly to the constructor of the connection.
You can pass your sql command text and the connection directly to the constructor of the command.
Please always use Parameters. Not only wil it save you from misplacing quotes but it will help ensure that correct datatypes are sent to the database. The most important thing is it helps protect you database from sql injection which can destroy your database. I had to guess at the datatypes in your database. Check the database and adjust the code accordingly.
Private ConnString As String = "server=localhost;user id=root;password=;database=bank"
Private Sub add()
Using cn As New MySqlConnection(ConnString)
Using cmd As New MySqlCommand("update cbank set Balance = Balance + #Balance where AccountID = #ID and PIN = #PIN;", cn)
cmd.Parameters.Add("#Balance", MySqlDbType.Decimal).Value = CDec(TextBox2.Text)
cmd.Parameters.Add("#ID", MySqlDbType.Int32).Value = CInt(TextBox1.Text)
cmd.Parameters.Add("#PIN", MySqlDbType.Int32).Value = CInt(TextBox3.Text)
cn.Open()
cmd.ExecuteNonQuery()
End Using
End Using
End Sub

Answer 2

Quotes problem.
Imports MySql.Data.MySqlClient
Public Class Form4
Public MysqlConn As MySqlConnection
Public cmd As New MySqlCommand
Public da As New MySqlDataAdapter
Public Sub MysqlConnection()
MysqlConn = New MySqlConnection()
'Connection String
MysqlConn.ConnectionString = "server=localhost;" _
& "user id=root;" _
& "password=;" _
& "database=bank"
'OPENING THE MysqlConnNECTION
MysqlConn.Open()
End Sub
Public Sub add()
Dim sql As String
Dim TempTable As New DataTable
sql = "update cbank set Balance = Balance + " & TextBox2.Text & "where AccountID = " & TextBox1.Text & "and PIN = " & TextBox3.Text & ";"
bind the connection and query
With cmd
.Connection = MysqlConn
.CommandText = sql
End With
da.SelectCommand = cmd
End Sub
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Me.Hide()
Form2.Show()
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
MysqlConnection()
add()
End Sub
Private Sub Form4_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
End Class