dataRow = dataSet.Tables(0).NewRow()
dataRow("time_in_am") = DateTime.Now
dataSet.Tables(0).Rows.Add(dataRow)

dataRow("time_in_am") = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")

Imports System.Runtime.CompilerServices

Public Module MyExtensions

    <Extension()>
    Public Function ToMySql(d As Date) As String
        Return d.ToString("yyyy-MM-dd HH:mm:ss")
    End Function

End Module

dataRow("time_in_am") = DateTime.Now.ToMySql()

Return d.toString("yyyy-MM-dd HH:mm:ss")