mysql - 如何选择在给定的表格结构中所做的最新更改？

我有一个表结构
id，trackid，table_name，操作，oldvalue，newvalue，字段，onetime

现在，如果我为相同的“ trackid”，相同的“ field”有3行，那么我该如何从三行中选择最新的？

即用于：


  id = 100 trackid = 152 table_name
  = jos_menu操作=更新旧值= IPL新值= IPLcccc
  字段=名称live = 0已更改一次=
  2010-04-30 17:54:39


和


  id = 101 trackid = 152 table_name =
  jos_menu操作=更新旧值
  = IPLcccc新值= IPL2222字段=名称有效= 0更改一次=
  2010-04-30 18:54:39


如您所见，secind条目是最新的更改，
现在我应该使用哪种查询从许多这样的行中获取唯一的和最新的行...


  更新

$distupdqry = "select DISTINCT trackid,table_name from jos_audittrail where live = 0 AND operation = 'UPDATE'";
$disupdsel = mysql_query($distupdqry);
$t_ids = array();
$t_table = array();
while($row3 = mysql_fetch_array($disupdsel))
{
    $t_ids[] = $row3['trackid'];
    $t_table[] = $row3['table_name'];
    //$t_table[] = $row3['table_name'];
}

//echo "<pre>";print_r($t_table);echo "<pre>";

//exit;
for($n=0;$n<count($t_ids);$n++)
{

      $qupd = "SELECT * FROM jos_audittrail WHERE operation = 'UPDATE'  AND trackid=$t_ids[$n] order by changedone DESC ";
    $seletupdaudit = mysql_query($qupd);
    $row4 = array();
    $audit3 = array();
    while($row4 = mysql_fetch_array($seletupdaudit))
    {
        $audit3[] = $row4;
    }


        $updatefield = '';
        for($j=0;$j<count($audit3);$j++)
        {
            if($j == 0)
            {

                if($audit3[$j]['operation'] == "UPDATE")
                {
                            //$insqry .= $audit2[$i]['operation']." ";
                            //echo "<br>";
                    $updatefield .= "UPDATE `".$audit3[$j]['table_name']."` SET ";

                }
            }

            if($audit3[$j]['operation'] == "UPDATE")
            {

                $updatefield .= $audit3[$j]['field']." = '".$audit3[$j]['newvalue']."', ";

            }

        }
        /*echo "<pre>";
    print_r($audit3);
    exit;*/
        $primarykey = "SHOW INDEXES FROM `".$t_table[$n]."` WHERE Key_name = 'PRIMARY'";
        $prime = mysql_query($primarykey);
        $pkey = mysql_fetch_array($prime);
        $updatefield .= "]";
        echo $updatefield = str_replace(", ]"," WHERE ".$pkey['Column_name']." = '".$t_ids[$n]."'",$updatefield);
}

在这里，我通过从最初描述的表（这里称为auditrail表）中获取记录来创建Update查询。

最佳答案

select * from TableName order by id DESC LIMIT 1

已编辑。是的，如果您想通过“ changedonetime” USE订购，可以。

select * from TableName order by changedonetime DESC LIMIT 1