Question

我想将以下sql查询转换为Linq： -

exec('SELECT * FROM (SELECT MAS.EmployeeId, MAS.ENTRY_DATE, IT.InDate 
IN_DATE, OT.InDate OUT_DATE, MAS.SHIFT_CODE, MAS.SHIFT_FLAG, CASE WHEN 
(IT.InDate IS NOT NULL) AND (OT.INDATE IS NOT NULL) THEN CASE WHEN IT.InDate = OT.InDate THEN ''FALSE'' ELSE ''OK'' END ELSE  ''FAIL'' END AS VALID FROM (SELECT EmployeeId, Time_Date1 ENTRY_DATE,Time_Field1 SHIFT_CODE, Time_Field2 
SHIFT_FLAG FROM [WWEGG8f9bf41c16].[TO_TempInOutNew] GROUP BY EmployeeId, Time_Date1, Time_Field1, Time_Field2) MAS LEFT JOIN [WWEGG8f9bf41c16].[TO_TempInOutNew] IT ON IT.EmployeeId=MAS.EmployeeId AND 
IT.Time_Date1=MAS.ENTRY_DATE AND IT.InOutFlag=''I'' LEFT JOIN [WWEGG8f9bf41c16].[TO_TempInOutNew] OT ON OT.EmployeeId=MAS.EmployeeId AND OT.Time_Date1=MAS.ENTRY_DATE AND OT.InOutFlag=''O'') MY_IN_OUT')

所以我在Linqer的帮助下做到了这一点： -

var qry = (from MY_IN_OUT in
                               (
                                   (from MAS in
                                        (
                                            (from TO_TempInOutNew in listTempInOutNew
                                             group TO_TempInOutNew by new
                                             {
                                                 TO_TempInOutNew.EmployeeId,
                                                 TO_TempInOutNew.Time_Date1,
                                                 TO_TempInOutNew.Time_Field1,
                                                 TO_TempInOutNew.Time_Field2
                                             } into g
                                             select new
                                             {
                                                 g.Key.EmployeeId,
                                                 ENTRY_DATE = g.Key.Time_Date1,
                                                 SHIFT_CODE = g.Key.Time_Field1,
                                                 SHIFT_FLAG = g.Key.Time_Field2
                                             }))
                                    join IT in listTempInOutNew
                                          on new { EmployeeId = Convert.ToInt32(MAS.EmployeeId), Time_Date1 = Convert.ToDateTime(MAS.ENTRY_DATE), InOutFlag = "I" }
                                      equals new { IT.EmployeeId, IT.Time_Date1, IT.InOutFlag } into IT_join
                                    from IT in IT_join.DefaultIfEmpty()
                                    join OT in listTempInOutNew
                                          on new { EmployeeId = Convert.ToInt32(MAS.EmployeeId), Time_Date1 = Convert.ToDateTime(MAS.ENTRY_DATE), InOutFlag = "O" }
                                      equals new { OT.EmployeeId, OT.Time_Date1, OT.InOutFlag } into OT_join
                                    from OT in OT_join.DefaultIfEmpty()
                                    select new
                                    {
                                        EmployeeId = (int?)MAS.EmployeeId,
                                        ENTRY_DATE = (DateTime?)MAS.ENTRY_DATE,
                                        IN_DATE = (DateTime?)IT.InDate,
                                        OUT_DATE = (DateTime?)OT.InDate,
                                        MAS.SHIFT_CODE,
                                        MAS.SHIFT_FLAG,
                                        VALID =
                                        IT.InDate != null &&
                                        OT.InDate != null ? (
                                        IT.InDate == OT.InDate ? "FALSE" : "OK") : "FAIL"
                                    }))
                           select new
                           {
                               MY_IN_OUT.EmployeeId,
                               MY_IN_OUT.ENTRY_DATE,
                               MY_IN_OUT.IN_DATE,
                               MY_IN_OUT.OUT_DATE,
                               MY_IN_OUT.SHIFT_CODE,
                               MY_IN_OUT.SHIFT_FLAG,
                               MY_IN_OUT.VALID
                           }).ToList();

它在位置OUT_DATE = (DateTime?)OT.InDate,给出了错误。 OT.InDate显示为null。不应该是这种情况。

对象引用未设置为对象的实例。

有关如何解决此问题的任何建议？

Answer 1

您正在使用左连接，因此对象IT和OT可能为空。替换选择部分如下。

select new
           {
        EmployeeId = (int?)MAS.EmployeeId,
        ENTRY_DATE = (DateTime?)MAS.ENTRY_DATE,
        IN_DATE = (DateTime?)IT != null ? IT.InDate : null,
        OUT_DATE = (DateTime?)OT != null ? OT.InDate : null,
        MAS.SHIFT_CODE,
        MAS.SHIFT_FLAG,
        VALID =
        IT != null && IT.InDate != null &&
        OT != null && OT.InDate != null ? (
        IT.InDate == OT.InDate ? "FALSE" : "OK") : "FAIL"
           }))

SQl查询转换为Linq错误

1 个答案: