Question

我的数据库表如下所示：

ScannerStatusHistoryID  DetectorID                 TimeStamp                    HBD1    HBD2    HWD1    HWD2    RC1    RC2     RC3      RC4
          1                 948         2017-03-17 08:44:34.0000000 +01:00       3        3      3        0      3      3       0        3
          2                 948         2017-03-17 09:44:34.0000000 +01:00       3        3      3        0      3      3       0        3
          3                 948         2017-03-17 10:44:34.0000000 +01:00       3        2      3        0      3      3       0        3
          4                 948         2017-03-17 11:44:34.0000000 +01:00       3        2      3        0      3      3       0        1
          5                 948         2017-03-17 12:44:34.0000000 +01:00       3        2      3        0      3      3       0        1

我有这样的查询：

[Query]
        public IQueryable<ScannerStatusHistory> GetScannerStatus(int detectorID)
        {
            var lastRow = ObjectContext.ScannerStatusHistories.Where(t => t.DetectorID == detectorID).OrderByDescending(d => d.TimeStamp).FirstOrDefault();
            //Get last changed row
            if (lastRow != null)
            {
                var lastChangeRow = ObjectContext.ScannerStatusHistories
                .Where(t => t.DetectorID == detectorID
                    && (t.HBD1 != lastRow.HBD1 || t.HBD2 != lastRow.HBD2 || t.HWD1 != lastRow.HWD1 || t.HWD2 != lastRow.HWD2 || t.RC1 != lastRow.RC1 || t.RC2 != lastRow.RC2 || t.RC3 != lastRow.RC3 || t.RC4 != lastRow.RC4))
                .OrderByDescending(d => d.TimeStamp)
                .FirstOrDefault();
                //Return next row
                if (lastChangeRow != null)
                {
                    return ObjectContext.ScannerStatusHistories
                     .Where(x => lastChangeRow.TimeStamp < x.TimeStamp
                         && x.DetectorID == detectorID)
                     .OrderBy(d => d.TimeStamp)
                     .Take(1);
                }
            }
            return ObjectContext.ScannerStatusHistories.Where(t => t.DetectorID == detectorID).OrderBy(d => d.TimeStamp).Take(1);
        }

它做什么，它搜索HBD1或HBD2或HWD1或HWd2或RC1或Rc2或Rc3或Rc4之间发生变化的最后一行。

根据示例我现在得到的结果是：

ScannerStatusHistoryID  DetectorID                 TimeStamp                    HBD1    HBD2    HWD1    HWD2    RC1    RC2     RC3      RC4
      4                   948         2017-03-17 11:44:34.0000000 +01:00         3        2      3        0      3      3       0        1

但这只是因为1列已更改。所以它会抓住那一排。但是，是否有可能为每行检查一次，并显示列已更改的日期。而不是1列已更改。

所以期望的结果是：

HBD1 = 2017-03-17 08:44:34.0000000 +01:00 
HBD2 = 2017-03-17 10:44:34.0000000 +01:00 
HWD1 = 2017-03-17 08:44:34.0000000 +01:00 
HWD2 = 2017-03-17 08:44:34.0000000 +01:00 
RC1 = 2017-03-17 08:44:34.0000000 +01:00 
RC2 = 2017-03-17 08:44:34.0000000 +01:00 
RC3 = 2017-03-17 08:44:34.0000000 +01:00 
RC4 = 2017-03-17 11:44:34.0000000 +01:00

我现在收到的结果：

HBD1 = 2017-03-17 11:44:34.0000000 +01:00
HBD2 = 2017-03-17 11:44:34.0000000 +01:00
HWD1 = 2017-03-17 11:44:34.0000000 +01:00
HWD2 = 2017-03-17 11:44:34.0000000 +01:00 
RC1 = 2017-03-17 11:44:34.0000000 +01:00
RC2 = 2017-03-17 11:44:34.0000000 +01:00
RC3 = 2017-03-17 11:44:34.0000000 +01:00
RC4 = 2017-03-17 11:44:34.0000000 +01:00

这可以在一个查询中执行，还是我必须执行8个单独的查询来检查每列的更改状态？

每行查找结果C＃

0 个答案: