Question

My problem is, when I query by a usual ID, like number with no segments = 1234567890, it works nicely.

But I need to query by some kind of segmented values or ID as = 123-4567-890, when I try by 123-4567-890 this id it does not query anything in mysql although in the database this 123-4567-890 ID is present.

So what is the possible solution to search by segmented value in mysql in VB.NET

Here is below, my trying codes in vb

Public Sub student()

    textbox1.text= "123-4567-890"
    Try
        dbConn()
        Dim myAdapter As New MySqlDataAdapter("Select studentID, batchID, studentStatus from student where studentID= " & textbox1.text, ServerString)
        Dim myDataTable As New DataTable
        myAdapter.Fill(myDataTable)

        If myDataTable.Rows.Count > 0 Then
            vrSID = myDataTable.Rows(0).Item("studentID")
            vrRecBatchID = myDataTable.Rows(0).Item("batchID")
            vrAttendanceStatus = myDataTable.Rows(0).Item("studentStatus")

            If vrSID = vrIDD Then                    
                If vrAttendanceStatus = "Active" Then
                    Console.Beep()
                    batchRoutine()                        
                Else
                    led3()
                    Console.Beep()
                End If
            End If
        Else
            Console.Beep()
            teacher()
        End If
    Catch ex As Exception
        Console.Beep()
        MsgBox ("Error")
    End Try
End Sub

Answer 1

When you are running into problems, the easiest way to solve them is to break things down to the simplest scenario. So instead of complicating things with table adapters and data tables, see what happens when you just send MySQL the query you ‘think’ works correctly.

So start out by seeing if you can get this to work, then go from there:

    Dim sql As String = "select id from mytable where id = '123-4567-890'"
    Using cnx As New MySqlConnection("connection_string")
        Using cmd As New MySqlCommand(sql, cnx)
            cnx.Open()

            Using reader As MySqlDataReader = cmd.ExecuteReader()

                Debug.Assert(reader.Read(), "No results")
                Trace.WriteLine(reader.GetValue(reader.Item(0)))
            End Using
        End Using
    End Using