Ambil data value dari database vb net mysql

Here's your SQL code:

SELECT idstudents FROM students WHERE idstudents = @TextBox1.Text

What's the point of pulling idstudents out when that's the value you're putting in? Worse, though, that's ALL you're pulling out, then you do this:

TextBox2.Text = reader[1]
TextBox3.Text = reader[2]
TextBox4.Text = reader[3]

which would require you to pull back at least four columns.

The modification mentioned in the comments may well get your code to execute but it's not the right way to go. It looks like you tried to use a parameter but failed. Do that but do it right, i.e.

Dim sql As String = "SELECT idstudents, otherColumnsHere FROM students WHERE idstudents = @idstudents"

Using connection As New MySqlConnection[myConnectionString],
      command As New MySqlCommand[sql, connection]
    command.Parameters.Add["@idstudents", MySqlDbType.Int32].Value = CInt[TextBox1.Text]
    conn.Open[]

    Using reader = command.ExecuteReader[]
        If reader.Read[] Then
            TextBox2.Text = reader[1]
            TextBox3.Text = reader[2]
            TextBox4.Text = reader[3]
        End If
    End Using
End Using

selamat sore rekan2 semua...

saya mau nanya nih,, gimana ya cara/ code untuk mengecek hasil dari query = NULL...???

saya menggunakan Mysql dan Vb.net 2010.

saya sudah mencoba dengan beberapa code seperti berikut, Namun Code Tersebut Hanya Membaca jika nilai dari querynya tidak NULL alias ada datanya...

code pertama :

        Dim strConn As String = "string koneksi kedatabasenya....."
        conn.ConnectionString = strConn
        conn.Open[]
CMD.Connection = conn
CMD.CommandText = "SELECT idsoal from tbl_soal_tes_seri_angka where substring[idsoal,3,1] ='1' order by idsoal desc"
DR = CMD.ExecuteReader
If DR.HasRows Then
 DR.Read[]
 If DR[0] Is DBNull.Value Then
   MessageBox.Show["DATA nya = NULL"]
   Label7.Text = "11"
 ElseIf DR[0] > 0 Then
   MessageBox.Show["sudah ada kode soal"]
   Label7.Text = DR[0]
 End If
End If

Code Kedua [Untuk Querynya Sama Yang Dirubah Hanya bagian pengecekan data NULLnya saja]:

While DR.Read[]
     If DR.IsDBNull[0] Then
       MessageBox.Show["Data Nya NULL"]
       Label7.Text = "11" & "1"

     Else
       MessageBox.Show["sudah ada kode soal"]
       Label7.Text = DR[0]
     End If
End While

DR.Close[]

code ketiga :

If Not IsDBNull[DR[0]] Then
    MessageBox.Show["sudah ada kode soal"]
    Label7.Text = DR[0]
Else
    MessageBox.Show["Data Nya NULL"]
    Label7.Text = "11" & "1"
End If

DR.Close[]

Kalo saya coba Querinya  dari mysqlnya seperti ini :

apakah ada yang salah di code saya..??

terima kasih...

By :

• Diedit oleh Jumat, 19 April 2013 09.53

Imports System.Data.OleDb
Imports System.Data.Odbc

Public Class Import_excel_to_mysql

Dim connexcel As OleDbConnection
Dim daexcel As OleDbDataAdapter
Dim dsexcel As DataSet
Dim cmdexcel As OleDbCommand
Dim drexcel As OleDbDataReader

Dim connodbc As odbcConnection
Dim daodbc As odbcDataAdapter
Dim dsodbc As DataSet
Dim cmdodbc As odbcCommand
Dim drodbc As odbcDataReader

Private Sub import_excel_to_mysql_Load[ByVal sender As System.Object, ByVal e As System.EventArgs] Handles MyBase.Load
Me.CenterToScreen[]
End Sub

Private Sub Button1_Click[ByVal sender As System.Object, ByVal e As System.EventArgs] Handles Button1.Click
On Error Resume Next
'OpenFileDialog1.Filter = "[*.xls]|*.xls|[*.xlsx]|*.xlsx|All files [*.*]|*.*"
OpenFileDialog1.ShowDialog[]
TextBox1.Text = OpenFileDialog1.FileName

connexcel = New OleDbConnection["provider=Microsoft.ace.OLEDB.12.0;data source=" & TextBox1.Text & ";Extended Properties=Excel 8.0;"]
connexcel.Open[]

Dim dtSheets As DataTable = connexcel.GetOleDbSchemaTable[OleDbSchemaGuid.Tables, Nothing]
Dim listSheet As New List[Of String]
Dim drSheet As DataRow

For Each drSheet In dtSheets.Rows
listSheet.Add[drSheet["TABLE_NAME"].ToString[]]
Next

For Each sheet As String In listSheet
ListBox1.Items.Add[sheet]
Next

End Sub

Private Sub ListBox1_SelectedIndexChanged[ByVal sender As System.Object, ByVal e As System.EventArgs] Handles ListBox1.SelectedIndexChanged
daexcel = New OleDbDataAdapter["select * from [" & ListBox1.Text & "]", connexcel]
dsexcel = New DataSet
daexcel.Fill[dsexcel]
DGV.DataSource = dsexcel.Tables[0]
DGV.ReadOnly = True
End Sub

Sub Koneksimysql[]
connodbc = New OdbcConnection["Driver=MySQL ODBC 5.1 Driver; SERVER=localhost; UID=root;DATABASE=importfromexcel;PORT=3306"]
connodbc.Open[]
End Sub

Private Sub Button2_Click[ByVal sender As System.Object, ByVal e As System.EventArgs] Handles Button2.Click

For baris As Integer = 0 To DGV.RowCount - 2
Call Koneksimysql[]
Dim simpan As String = "insert into hasilimport values['" & DGV.Rows[baris].Cells[0].Value & "','" & DGV.Rows[baris].Cells[1].Value & "']"
cmdodbc = New OdbcCommand[simpan, connodbc]
cmdodbc.ExecuteNonQuery[]
Next
MsgBox["data berhasil disimpan"]
DGV.Columns.Clear[]
End Sub

End Class