mysql - 循环数据库表，依次获取每条记录的所有值

Question

我需要获取表中每条记录的所有值，这样我就可以将它们添加到文本文件日志中，每行一条记录，然后从数据库中删除它们。我对此很陌生，并且搜索了如何将 SQL 查询结果添加到数组或通用列表中，但我并不完全理解它们。

到目前为止我所拥有的是:

Private Sub btnClearAll_Click(sender As Object, e As EventArgs) Handles btnClearAll.Click
        conn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=E:\Application Programming\Project\Issue Logger\Database\IssueLoggerDB.accdb"
        Dim strSQl = "TRUNCATE TABLE CurrentJobs"

        Dim commandInsert As New OleDbCommand
        commandInsert.CommandText = strSQl
        commandInsert.Connection = conn
        commandInsert.Connection.Open()
        commandInsert.ExecuteNonQuery()

        Me.ReportViewer1.RefreshReport()

    End Sub

这是一个大学项目，上面是我们如何做到这一点的，但是我在研究过程中没有发现任何类似的东西。

Answer 1

请随意使用此程序:

Private Sub DataTableToTextFile()
    Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=E:\Application Programming\Project\Issue Logger\Database\IssueLoggerDB.accdb"

    Using conn As OleDbConnection = New OleDbConnection(connString)
        Dim dt As New DataTable
        conn.Open()
        'Change the query. It's not a good practice to use '*' in your select queries. Please, use the column names instead.
        Dim dataAdapter As New OleDbDataAdapter("SELECT * FROM CurrentJobs", conn)
        dataAdapter.Fill(dt)

        'Change the path to your desired path
        Dim exportPath As String = "C:\Logs\"
        Dim exportFileName As String = "log.txt"

        'If directory does not exists, create it
        If Not Directory.Exists(exportPath) Then
            Directory.CreateDirectory(exportPath)
        End If

        'Write data into the text file
        Dim writer As New StreamWriter(exportPath + exportFileName)
        Try
            Dim sb As New StringBuilder

            For Each row As DataRow In dt.Rows
                sb = New StringBuilder
                For Each col As DataColumn In dt.Columns
                    sb.Append(row(col.ColumnName))
                Next
                writer.WriteLine(sb.ToString())
            Next
        Catch ex As Exception
            Throw ex
        Finally
            If Not writer Is Nothing Then writer.Close()
        End Try

        'Finally clean database table
        Dim strSQl = "Delete From CurrentJobs"
        Dim commandDelete As New OleDbCommand(strSQl, conn)
        'execute
        commandDelete.ExecuteNonQuery()
        'close connection
        conn.Close()
    End Using
End Sub