VB的MySQL AddWithValue沒有通過價值成功

Question

我有以下的VB代碼

Dim cmd As New MySqlCommand("SELECT code FROM decoder WHERE ann_id = @aid", conn) 

cmd.Parameters.AddWithValue("@aid", 1) 

Dim reader As MySqlDataReader = cmd.ExecuteReader() 

的reader.Read（），然後給了我什麼，但是，如果我通過

Dim cmd As New MySqlCommand("SELECT code FROM decoder WHERE ann_id = 1", conn) 

Dim reader As MySqlDataReader = cmd.ExecuteReader() 

更換代碼

reader.Read（）給出正確的結果。嘗試使用添加，而不是幫助。我在這裏錯過了什麼？

非常感謝，

Answer 1

刪除@

Dim cmd As New MySqlCommand("SELECT code FROM decoder WHERE ann_id = @aid", conn) 
cmd.Parameters.AddWithValue("aid", 1) 
Dim reader As MySqlDataReader = cmd.ExecuteReader() 

Answer 2

Private Sub ButtonInsert_Click(sender As Object, e As EventArgs) Handles ButtonInsert.Click 
    Dim conn As New MySqlConnection 
    Dim cmd As New MySqlCommand 

    conn.ConnectionString = Me.Tag.ToString 

    Try 
     conn.Open() 
     cmd.Connection = conn 

     cmd.CommandText = "INSERT INTO myTable VALUES(NULL, @number, @text)" 
     cmd.Prepare() 

     cmd.Parameters.AddWithValue("@number", 1) 'sets @number to be numeric 
     cmd.Parameters.AddWithValue("@text", "One") 'sets @text to be characters 

     For i = 1 To 1000 

      cmd.Parameters("@number").Value = i 
      cmd.Parameters("@text").Value = "A string value" 

      cmd.ExecuteNonQuery() 
     Next 
    Catch ex As MySqlException 
     MessageBox.Show("Error " & ex.Number & " has occurred: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error) 
    End Try