聯合從2選擇加入

Question

請大家我需要關於選擇語法的幫助。

我需要從連接兩個選擇結果的聯合。

我試圖解釋

SELECT FROM 2 TABLE BY JOIN 
UNION 
SELECT FROM 2 OTHER TABLE BY UNION 

OR

我想：

select .... join.... data from table2for union 
union 
select .... join ... data from table1 for union 

表我會聯盟是從加入2表的結果。

對於其他數據的理解：

tabA1 
codice 
nome 
totale 
JOIN 
tabA2 
restocodice 
restonome 

UNION 

tabB1 
codiceconf 
nomeconf 
totaleconf 
JOIN 
tabB2 
restocodiceconf 
restonomeconf 

我希望我解釋。

Answer 1

select * 
from taba1 
left join taba2 
on taba1.col=taba2.col 

union 

select * 
from tabb1 
left join tabb2 
on tabb1.col=tabb2.col 

Answer 2

這是一般結構：

SELECT cols 
FROM table1 
JOIN table2 ON join-conditions 
WHERE more-conditions 

UNION 

SELECT cols 
FROM table3 
JOIN table4 ON join-conditions 
WHERE more-conditions