$金额合计=mysql_fetch_array(mysql_query("select  sum(money_amount) from finance_table   
where date_time between  '".$_POST['start_date_time']."' and   '".$_POST['end_date_time']."' and
      primary_classification ='".$_POST['primary_classification']."' and
      secondary_classification = '".$_POST['secondary_classification']."' and      
      remarks like '%".$_POST['remarks']."%' and
      increase_decrease  ='".$_POST['increase_decrease']."' and
      money_amount = $_POST['money_amount'] and      
      unit_price =$_POST['unit_price']
      "));

      money_amount
      unit_price

这两个都是数值型