SQL-如何更新主表，如果值是从2个不同的表中存在的？

Question

我一直想弄清楚如何创建一个SQL查询来更新主表，如果值是从2个不同的表中存在的？

例如：

Table1 (Main) 
Employee Number 
Name 
First Name 
Document Name 
Filename 
Original fileName 
DL_Status 

Table 2 (list table) 
Employee Number 
Document Name 
Original Filename 

Table 3(DIR list) 
Original fileName 
created 
extension file name 

输出： 的DL_Status应该被标记为“已完成”和原始文件名从表2的条目仅当原始文件名从表3存在来填充？

Answer 1

您可以在表2和表3上应用连接，然后编写脚本将数据更新到主表 注意：如果数据被明确提及，则答案将更具体。

Answer 2

尝试这样：

update table1 
set dl_status = a.dl_status, 
Original_Filename =a.Original_Filename 
from 
(select t2.Employee Number, 'Completed' as dl_status,t2.Original_Filename 
from table2 t2,table3 t3 
where t2.Original_Filename= t3.Original_Filename) a 
where a.Employee Number = table1.Employee Number 

Answer 3

最有可能

UPDATE m 
SET [DL_Status] ='Completed', 
    [Original fileName] = f.[Original fileName] 
FROM [Main] m 
JOIN [list table] l ON l.[Employee Number] = m.[Employee Number] AND l.[Document Name] = m.[Document Name] 
JOIN [DIR list] f ON l.[Original fileName] = f.[Original fileName] 
-- optionally 
WHERE m.[DL_Status] <> 'Completed' OR m.[Original fileName] <> f.[Original fileName]