在Linq-to-SQL查詢上需要幫助（也許是嵌套查詢嗎？）

Question

我正在尋求有關SQL的linq查詢的幫助。

這是我的數據庫圖的一部分： https : //imgur.com/xFBUm3q

我的問題在於以下關系： tbl_607_bottle和tbl_607_gaz_reporting ，我可以為一個瓶子提供多個報告，但是報告只能有一個瓶子。

我執行此請求，但並不令人滿意。

var GazReportingWizardViewModel = 
    (from gr in db.tbl_607_gaz_reporting  
     join a in db.tbl_607_actors on gr.FK_ID_actors equals a.id  
     join bo in db.tbl_607_bottle on gr.FK_ID_bottle equals bo.ID  
     join loc in db.tbl_607_location on bo.FK_ID_location equals loc.ID  
     join cc in db.tbl_607_conformity_certificate on bo.FK_ID_conformity_certificate equals cc.ID  
     join j in db.tbl_607_join_bottle_gaz on bo.ID equals j.FK_ID_bottle  
     join g in db.tbl_607_gaz on j.FK_ID_gaz equals g.ID  
     join od in db.tbl_607_order_details on g.FK_ID_order_details equals od.ID  
     where loc.ID == Process   
     select new GazReportingWizardViewModel  
                {  
                    bottle_conti_number = bo.bottle_conti_number,  
                    pressure_value = gr.pressure_value,  
                    reporting_date = gr.reporting_date,  
                    first_name = gr.tbl_607_actors.first_name,  
                    last_name = gr.tbl_607_actors.last_name,  
                    expiration_date = cc.expiration_date,  
                    content = od.content_comments  
                }).Distinct()
                  .OrderBy(t => t.reporting_date)
                  .ToList();  

我想要每個瓶子的最新報告，但它返回每個瓶子的所有報告。 您對解決方案有想法嗎？

感謝您的時間

Answer 1

非常感謝！ 當解決方案如此簡單時，我堅持嘗試通過單個查詢解決問題。

var GazReportingWizardViewModel = (from gr in db.tbl_607_gaz_reporting
                                   join a in db.tbl_607_actors on gr.FK_ID_actors equals a.id
                                   join bo in db.tbl_607_bottle on gr.FK_ID_bottle equals bo.ID
                                   join loc in db.tbl_607_location on bo.FK_ID_location equals loc.ID
                                   join cc in db.tbl_607_conformity_certificate on bo.FK_ID_conformity_certificate equals cc.ID
                                   join j in db.tbl_607_join_bottle_gaz on bo.ID equals j.FK_ID_bottle
                                   join g in db.tbl_607_gaz on j.FK_ID_gaz equals g.ID
                                   join od in db.tbl_607_order_details on g.FK_ID_order_details equals od.ID
                                   where loc.ID == Process 
                                   select new GazReportingWizardViewModel
                                   {
                                    bottle_conti_number = bo.bottle_conti_number,
                                    pressure_value = gr.pressure_value,
                                    reporting_date = gr.reporting_date,
                                    first_name = gr.tbl_607_actors.first_name,
                                    last_name = gr.tbl_607_actors.last_name,
                                    expiration_date = cc.expiration_date,
                                    content = od.content_comments
                                    }).ToList();

 var res = from element in GazReportingWizardViewModel
           group element by element.bottle_conti_number
           into groups
           select groups.OrderByDescending(p => p.reporting_date).First();