how to send a multiple message using datagridview in selecting a checkbox in vb.net? - vb.net

Question

Here is my code:
'for clicking the datagridview
Private Sub DataGridView1_CellContentClick_1(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
Try
MySqlConnection.ConnectionString = "Server=localhost; User=root;Password='';Database=lrbhams;"
MySqlConnection.Open()
Dim state3 As String = "select boarder_fname, boarder_contact, guardian, guardian_number from boarders_info"
Dim command As New MySqlCommand(state3, MySqlConnection)
'command.Connection.Open()
command.ExecuteNonQuery()
MySqlConnection.Close()
If DataGridView1.Rows(e.RowIndex).Cells(2).Value Then
TextBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(2).Value
ElseIf DataGridView1.Rows(e.RowIndex).Cells(4).Value Then
TextBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(4).Value
End If
Catch ex As Exception
MsgBox(ex.ToString)
End Try
''
End Sub
For sending message:
Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
Dim message As String
'Dim reader As MySqlDataReader
message = RichTextBox1.Text
If send_sms.SerialPort.PortName = send_sms.portName Then
send_sms.SerialPort.Write("AT" & vbCrLf)
send_sms.SerialPort.Write("AT+CMGF=1" & vbCrLf)
send_sms.SerialPort.Write("AT+CMGS=" & Chr(34) & TextBox1.Text & Chr(34) & vbCrLf)
send_sms.SerialPort.Write(message & Chr(26))
MsgBox("Text Message Successfully Send !!!")
Try
Dim connectString As String
Dim conn As New MySqlConnection
Dim reader As MySqlDataReader
Dim command As MySqlCommand
'Dim mysqlQuery As String
connectString = "server=localhost;user=root;database=lrbhams"
conn = New MySqlConnection(connectString)
Dim query As String
conn.Open()
query = "INSERT into admin_log_attendance (action,contact_number, date) VALUES ('" & RichTextBox1.Text & "','" & TextBox1.Text & "', '" & Date.Today & "')"
command = New MySqlCommand(query, conn)
reader = Command.ExecuteReader
conn.Close()
Catch ex As Exception
MsgBox(ex.Message)
End Try
End If
End Sub

Answer 1

MySqlConnection is a class in the MySql.Data.MySqlClient namespace. It is not a static class so it must be instantiated with the New keyword. You cannot set properties or call methods on the class itself. You must created an instance of the class. It is best practice to use `Using...End Using blocks for database objects. It will ensure that the database objects are closed and disposed even if there is an error.
A Select statement is not a NonQuery. Insert, Update and Delete statements can be run with command.ExecuteNonQuery but not Select. A Select query can be run with .ExecuteScalar if a single piece of data is expected or .ExecuteReader if several columns and/or rows are expected.
You can't just execute a Select command and expect something to happen. I suspect you want to display the data in your grid so let's fill a DataTable (an in memory representation of the records returned) with the .Load method then bind it to the DataGridView.
No need to close the connection because the Using block will close it.
If you call .ToString on a class that doesn't override the method you will just get the fully qualified name of the class. The Exception class provides a Property called Message which you can use.
The filling of the DataGridView will go in a separate method which you can call from Form.Load.
Now that there is data in the DataGridView you can click on it and the CellContentClick event will fire. I hope Cell(2) and Cell(4) Booleans because that is the only why your If statement will work. The necessity of the conversion code and .ToString will be obvious once you turn on Option Strict. (See my comment)
That's enough for now. With all this and Option Strict you should be able to fix the second part of your code.
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
RetrieveRecordsForDataGridView()
End Sub
Private Sub RetrieveRecordsForDataGridView()
Dim dt As New DataTable
Try
Using cn As New MySqlConnection("Server=localhost; User=root;Password='';Database=lrbhams;")
Dim state3 As String = "select boarder_fname, boarder_contact, guardian, guardian_number from boarders_info"
Using command As New MySqlCommand(state3, cn)
cn.Open()
dt.Load(command.ExecuteReader())
End Using
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
If CBool(DataGridView1.Rows(e.RowIndex).Cells(2).Value) Then
TextBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(2).Value.ToString
ElseIf CBool(DataGridView1.Rows(e.RowIndex).Cells(4).Value) Then
TextBox1.Text = DataGridView1.Rows(e.RowIndex).Cells(4).Value.ToString
End If
End Sub