Question

这是一个linq查询，以及表＆＃34; Timesheet_Log＆＃34;有DT_CR列的类型为DateTime，我想用最新的DT_CR日期获取查询，怎么可能？

  var getEmployeeNames = (from emps in reslandentity.EMPLOYEE
                                join timesheet in reslandentity.TIMESHEET on emps.ID equals timesheet.RES_ID
                                join weekcal in reslandentity.WEEK_CALENDER on timesheet.WEEK_CAL_ID equals weekcal.ID
                                join log in reslandentity.TIMESHEET_LOG on timesheet.ID equals log.TIMESHEET_ID
                                join workflow in reslandentity.TIMESHEET_WORKFLOW on log.WORKFLOW_ID equals workflow.ID                                    
                                where weekcal.WEEK_START_DT.Month == month                                    
                                orderby log.DT_CR select new TimesheetModel
                                {
                                    EMP_ID = emps.ID,
                                    EMPLOYEE_NAME = emps.FIRST_NAME + " " + emps.LAST_NAME,
                                    RES_TYPE = workflow.ORG_RES_TYPE,
                                    EMP_STATUS = workflow.ACTION,
                                    SDate = weekcal.WEEK_START_DT,
                                    EDate = weekcal.WEEK_END_DT,
                                    DT_CR=log.DT_CR
                                }).Distinct().ToList();
   model.GetTimeSheetDetails = getEmployeeNames;

请帮我查询。

Answer 1

如果你只想要一个结果或一个结果列表（每张时间表1个），你就不清楚了。

如果你只需要一个结果，那么lti Tyangi的答案就可以了。

如果您需要每个时间表的结果，您可以尝试以下方法：

var getEmployeeNames = (from emps in reslandentity.EMPLOYEE
                            join timesheet in reslandentity.TIMESHEET on emps.ID equals timesheet.RES_ID
                            join weekcal in reslandentity.WEEK_CALENDER on timesheet.WEEK_CAL_ID equals weekcal.ID
                            join mxLog in (
                                from lg in reslandentity.TIMESHEET_LOG
                                group lg by lg.TIMESHEET_ID into lgGrp
                                select new {lgGrp.Key, DT_CR = lgGrp.Max(x => x.DT_CR)}
                            ) on timesheet.ID equals mxLog.Key
                            join log in reslandentity.TIMESHEET_LOG on new { a = mxLog.Key, b = mxLog.DT_CR} equals new{ a = log.TIMESHEET_ID, b = log.DT_CR}
                            join workflow in reslandentity.TIMESHEET_WORKFLOW on log.WORKFLOW_ID equals workflow.ID                                    
                            where weekcal.WEEK_START_DT.Month == month                                    
                            orderby log.DT_CR select new TimesheetModel
                            {
                                EMP_ID = emps.ID,
                                EMPLOYEE_NAME = emps.FIRST_NAME + " " + emps.LAST_NAME,
                                RES_TYPE = workflow.ORG_RES_TYPE,
                                EMP_STATUS = workflow.ACTION,
                                SDate = weekcal.WEEK_START_DT,
                                EDate = weekcal.WEEK_END_DT,
                                DT_CR=log.DT_CR
                            }).Distinct().ToList();
   model.GetTimeSheetDetails = getEmployeeNames;

这里我们加入每个时间表的日志分组以获取每个时间表的最大日期，然后根据时间表的ID和该日期加入日志

Answer 2

 var getEmployeeNames = (from emps in reslandentity.EMPLOYEE
                            join timesheet in reslandentity.TIMESHEET on emps.ID equals timesheet.RES_ID
                            join weekcal in reslandentity.WEEK_CALENDER on timesheet.WEEK_CAL_ID equals weekcal.ID
                            join log in reslandentity.TIMESHEET_LOG on timesheet.ID equals log.TIMESHEET_ID
                            join workflow in reslandentity.TIMESHEET_WORKFLOW on log.WORKFLOW_ID equals workflow.ID                                    
                            where weekcal.WEEK_START_DT.Month == month                                    
                            //orderby log.DT_CR 
                            select new TimesheetModel
                            {
                                EMP_ID = emps.ID,
                                EMPLOYEE_NAME = emps.FIRST_NAME + " " + emps.LAST_NAME,
                                RES_TYPE = workflow.ORG_RES_TYPE,
                                EMP_STATUS = workflow.ACTION,
                                SDate = weekcal.WEEK_START_DT,
                                EDate = weekcal.WEEK_END_DT,
                                DT_CR=log.DT_CR
                            }).OrderByDescending(x=>x.DT_CR).FirstorDefault();

OR

 var getEmployeeNames = (from emps in reslandentity.EMPLOYEE
                            join timesheet in reslandentity.TIMESHEET on emps.ID equals timesheet.RES_ID
                            join weekcal in reslandentity.WEEK_CALENDER on timesheet.WEEK_CAL_ID equals weekcal.ID
                            join log in reslandentity.TIMESHEET_LOG on timesheet.ID equals log.TIMESHEET_ID
                            join workflow in reslandentity.TIMESHEET_WORKFLOW on log.WORKFLOW_ID equals workflow.ID                                    
                            where weekcal.WEEK_START_DT.Month == month                                    
                            //orderby log.DT_CR 
                            select new TimesheetModel
                            {
                                EMP_ID = emps.ID,
                                EMPLOYEE_NAME = emps.FIRST_NAME + " " + emps.LAST_NAME,
                                RES_TYPE = workflow.ORG_RES_TYPE,
                                EMP_STATUS = workflow.ACTION,
                                SDate = weekcal.WEEK_START_DT,
                                EDate = weekcal.WEEK_END_DT,
                                DT_CR=log.DT_CR
                            }).OrderByDescending(x=>x.DT_CR).ToList().Take(1);

如何在linq中获取具有Max Date的数据

2 个答案: