Question

这也许很简单，但我不知道。基本上我将C＃linq查询转换为sql查询以减少执行时间。但是我不擅长sql查询，所以我发现很难。这是我的两个桌子及其记录

HRMS_EodRecord

SELECT EmployeeId,HRMS_EodReferenceFk,ActualAmount FROM HRMS_EodRecord

结果如下：

EmployeeId    HRMS_EodReferenceFk    ActualAmount
   101                 1                 1000
   101                 2                  999
   101                 3                    0

和另一个桌子

HRMS_EodReference

SELECT ID FROM HRMS_EodReference

结果如下：

我想将这两个表的数据和结果相结合

 EmployeeId    HRMS_EodReferenceFk    ActualAmount
   101                 1                 1000
   101                 2                  999
   101                 3                    0
   101                 4                    0 ----From HRMS_EodReference
   101                 5                    0 ----From HRMS_EodReference

Answer 1

在2个表中有关EmployeeId的相关信息不足，但这可以帮助您入门：

SELECT  rec.EmployeeId              --> Insufficient info on relationship
        , ref.ID                    AS HRMS_EodReferenceFk
        , CASE WHEN rec.ActualAmount IS NULL THEN 0 ELSE rec.ActualAmount END
                                    AS ActualAmount
FROM    HRMS_EodReference           AS ref
        LEFT JOIN HRMS_EodRecord    AS rec ON rec.HRMS_EodReferenceFk = ref.ID;

Answer 2

您可能正在寻找SQL“右连接”，编号：https://www.w3schools.com/sql/sql_join_right.asp

RIGHT JOIN关键字返回右表（表2）中的所有记录，并返回左表（表1）中的匹配记录。如果没有匹配项，则结果从左侧为NULL。

 SELECT HRMS_EodRecord.EmployeeId, HRMS_EodReference.ID, HRMS_EodRecord.ActualAmount FROM HRMS_EodRecord
 RIGHT JOIN HRMS_EodReference ON HRMS_EodRecord.HRMS_EodReferenceFk = HRMS_EodReference.ID

Answer 3

如果您只有一个员工ID，

select 101 as EmployeeId,
       ref.ID as HRMS_EodReferenceFk
       coalesce(rec.ActualAmount, 0) as ActualAmount
from HRMS_EodReference ref left join
     HRMS_EodRecord rec 
     on rec.HRMS_EodReferenceFk = ref.ID;

不过，大概您一次想要许多员工使用。在这种情况下，请使用cross join生成行，然后使用left join引入现有值：

select e.EmployeeId,
       ref.ID as HRMS_EodReferenceFk
       coalesce(rec.ActualAmount, 0) as ActualAmount
from (select distinct EmployeeId
      from HRMS_EodRecord
     ) cross join
     HRMS_EodReference ref left join
     HRMS_EodRecord rec 
     on rec.EmployeeId = e.EmployeeId and
        rec.HRMS_EodReferenceFk = ref.ID;

将两个表数据合并为一个

3 个答案: