mysql - 多个 MySQL 查询

Question

如果我只添加一个查询，例如 hostnameQuery，则代码可以正常工作，正如您所看到的，我尝试添加多个查询。

我尝试在 MySqlCommand 上使用 + 和 &，但返回了语法错误。

Dim hostnameQuery As String = "SELECT `HOSTNAME` FROM `m1` WHERE 1"
    Dim osQuery As String = "SELECT `OS` FROM `m1` WHERE 1"
    Dim SQLConnection As New MySqlConnection(My.Settings.connStr)
    Dim cmd As New MySqlCommand(hostnameQuery & osQuery, SQLConnection)

    Try
        SQLConnection.Open()
        cmd.ExecuteNonQuery()
        Dim reader As MySqlDataReader
        reader = cmd.ExecuteReader
        While reader.Read
            main.Label64.Text = (reader.GetString(0))
            main.Label65.Text = (reader.GetString(0))
        End While
    Catch ex As Exception
        MsgBox(ex.Message.ToString)
    Finally
        SQLConnection.Close()

    End Try

Answer 1

尝试:

Dim hostnameQuery As String = "SELECT `HOSTNAME` FROM `m1` WHERE 1 UNION ALL (SELECT `OS` FROM `m1` WHERE 1)";

或者你为什么不呢(因为你查询了 1 个表):

 Dim hostnameQuery As String = "SELECT `HOSTNAME`,`OS`  FROM `m1` WHERE 1 ";

 .....

While reader.Read
            main.Label64.Text = (reader.GetString(0))
            main.Label65.Text = (reader.GetString(1))