在同一臺服務器上加入來自兩個不同數據庫的查詢？

Question

我在同一臺服務器上有兩個DB。對於每個正確工作的數據庫，我有兩個簡單的選擇查詢。但是，當它們合併成一個連接時，它們就會失敗。我想解決這個問題。

僞 -

select * 
from (select columns from DB1) as D1 
inner join 
select * 
from (select columns from DB2 where some valid condition) as D2 
on D1.column1 = D2.column1 

錯誤 -

Incorrect syntax near the keyword 'SELECT'. (ie second "outer" select) 
Incorrect syntax near the keyword 'on'. 

Answer 1

哎呀 - 我所要做的就是這一點 -

select * 
from (select columns from DB1) as D1 
inner join 
--select * 
--from 
(select columns from DB2 where some valid condition) as D2 
on D1.column1 = D2.column1 

見註釋行。刪除它們，它應該工作。

注意，包括從D2選定列，把D2列在最上面的select語句。

select col1b, col2c 
from (select col1a, col1b from DB1) as D1 
inner join 
--select * 
--from 
(select col2a, col2b, col2c from DB2 where some valid condition) as D2 
on D1.col1a = D2.col2a 

這將顯示col1b和col2c。

Answer 2

select * 
from DataBaseName.ShemaName.TableName1 D1 inner join DataBaseName.ShemaName.TableName2 D2 
on D1.column1 = D2.column1 
WHERE Somecondition