VB.NET中的WHERE语句

Question

For a school assignment I need to name computer based on their MAC-Adress. I have a mySQL table with two columns Mac-Adress and Computername. I want to use the computer's mac adress via following code, which works.

Declaration of the globals

Public connStr As String = "Database=Mac;" & _ "Data Source=localhost;" & _ "User Id=root;Password=" Public mac_adress As String

Getting the Mac Adress

Public Sub MacAdres() Dim nic As NetworkInterface = Nothing

  For Each nic In NetworkInterface.GetAllNetworkInterfaces mac_adress = nic.GetPhysicalAddress.ToString Next End Sub 

However, when I want to create the WHERE statement, I get an error. I'm using the following code for the WHERE statement.

 Public Sub retriveData() Try Dim query As String = "SELECT * FROM 'mactable' WHERE 'Mac-adres' = '" & mac_adress & "'" Dim connection As New MySqlConnection(connStr) Dim cmd As New MySqlCommand(query, connection) connection.Open() Dim reader As MySqlDataReader reader = cmd.ExecuteReader() While reader.Read() MessageBox.Show(reader.GetString(1)) End While reader.Close() connection.Close() Catch ex As Exception Console.WriteLine(ex.Message) End Try End Sub 

What am I doing wrong?

A first chance exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in >MySql.Data.dll

Answer 1

我认为您不需要表名或字段名上的引号，并且可以删除连字符。

Dim query As String = "SELECT * FROM mactable WHERE MacAdres = '" & mac_adress & "'"

Answer 2

Solved it by using these: "`" instead of these '. Thats rather peculiar, but it solved it.