order by 子句打破了 Play 2.1.2 中的异常选择查询答案

【问题标题】：order by clause is breaking Anorm select query in Play 2.1.2order by 子句打破了 Play 2.1.2 中的异常选择查询
【发布时间】：2014-02-15 19:32:42
【问题描述】：

我在 Play 2.1.2 中有以下代码

def list(startDate:String, endDate:String,  page:Option[Int], pageSize:Option[Int] ) = {
    DB.withConnection { implicit connection =>
        val c = SQL("""
              select 
                employeeId,
                CertType, 
                ct.name, 
                applicable,
                due,
                year(due) as yeardue,   month(due) as monthdue, day(due) as daydue, 
                year(completed),     month(completed),     day(completed), 
                year(last),       month(last),       day(last), 
                status 
              from cert 
              join certtype ct on CertType=ct.code
              where due<{endDate} and due>{startDate} and CertType not in (500,600)
              order by due
            """ 
          )
          .on('index -> page, 'pageSize -> pageSize , 'startDate -> startDate, 'endDate->endDate)().collect{
            case Row(  
                  employeeId:Long,
                  certType:Int, 
                  name:String, 
                  applicable:Int,
                  Some(due:java.sql.Date),
                  Some(yeardue:Long),      Some(monthdue:Long),     Some(daydue:Long),
                  Some(yearcompleted:Long),  Some(monthcompleted:Long),   Some(daycompleted:Long),
                  Some(yearlast:Long),    Some(monthlast:Long),     Some(daylast:Long),
                  status:Long) =>
                  Reminder(
                      employeeId, 
                      certType, 
                      name,  
                      if (applicable>0) true else false, 
                      makeDate(yeardue,    monthdue,    daydue),  
                      makeDate(yearcompleted,  monthcompleted,  daycompleted),  
                      makeDate(yearlast,    monthlast,    daylast),  
                      status);
        }
        c.toList
    }
}

唯一可行的方法是删除“order by”子句。
Order by 仅适用于像 ct.name 这样的字符串字段。否则，列表为空。

我没有由此产生的错误消息，只是一个空白列表。

【问题讨论】：

从效率的角度来看，实际上在代码中排序通常比在数据库中排序更受欢迎。此外，按 SQL 顺序排列的 AFAIK 也适用于日期。可能是 Anorm 的问题？你能用 Slick 代替吗？或者只是不要在数据库中订购。此外，due between startDate and endDate 的效率也稍高一些。
嗯...不确定在代码中排序是否更有效，但感谢您提供有关使用“介于”作为日期范围的提示。

标签： mysql anorm

【解决方案1】：

好的，现在可以了，我不知道为什么。

这是工作版本：

def list(startDate:String, endDate:String,  page:Option[Int], pageSize:Option[Int] ) = {
    DB.withConnection { implicit connection =>
        val c = SQL("""
                        select 
                            employeeId,
                            CertType, 
                            ct.name, 
                            applicable,
                            due,
                            completed,
                            last,
                            status 
                        from cert 
                        join certtype ct on CertType=ct.code
                        where due between {startDate} and {endDate} and CertType not in (500,600)
                        order by due
                    """ 
            )
            .on('index -> page, 'pageSize -> pageSize , 'startDate -> startDate, 'endDate->endDate)().collect{
                case Row(   
                            employeeId:Long,
                            certType:Int, 
                            name:String, 
                            applicable:Int,
                            Some(due:java.sql.Date),        // optional to handle potential null value
                            Some(completed:java.sql.Date),  // optional to handle potential null value
                            last:java.sql.Date,             // this is probably required to NOT be optional since it is a PK in the schema (?)
                            status:Long) =>
                    Reminder(
                            employeeId, 
                            certType, 
                            name,  
                            if (applicable>0) true else false, 
                            new DateTime(due.       getTime()).toString("yyyy-MM-dd"),
                            new DateTime(completed. getTime()).toString("yyyy-MM-dd"),
                            new DateTime(last.      getTime()).toString("yyyy-MM-dd"),
                            status);
        }
      c.toList
    }
  }

【讨论】：