SQL - UNION，按顺序执行时优先于第一个选择语句

Question

我试图首先打印出来自“GermanDB”数据库的结果，同时还显示来自波士顿数据库但不在德国数据库中的所有内容。这可以在一个查询中完成吗？

我的查询(粗体部分起作用但没有按照我想要的方式排序)

select * from (  
SELECT DISTINCT a.ProductRef  
FROM GERMANDB.dbo.LOCATIONS AS a INNER JOIN GERMANDB.dbo.ITEMS AS b ON a.ProductRef =   b.ProductRef   
WHERE b.ACTIVE=1  
) ta  
UNION select * from  
SELECT DISTINCT c.ProductRef  
FROM BOSTONDB.dbo.LOCATIONS AS c INNER JOIN BOSTONDB.dbo.ITEMS AS d ON c.ProductRef =   d.ProductRef   
WHERE c.ACTIVE=1 (c.ProductRef NOT IN   
(SELECT ProductRef FROM GERMANDB.dbo.ITEMS where ACTIVE=1))  
) tb  
order by ta.ProductRef** , tb.productRef

Answer 1

只需添加一个字段来表示优先级。像这样:

select *, 0 as Priority from (  
SELECT DISTINCT a.ProductRef  
FROM GERMANDB.dbo.LOCATIONS AS a INNER JOIN GERMANDB.dbo.ITEMS AS b ON a.ProductRef =   b.ProductRef   
WHERE b.ACTIVE=1  
) ta  
UNION select *, 1 as Priority from  
SELECT DISTINCT c.ProductRef  
FROM BOSTONDB.dbo.LOCATIONS AS c INNER JOIN BOSTONDB.dbo.ITEMS AS d ON c.ProductRef =   d.ProductRef   
WHERE c.ACTIVE=1 (c.ProductRef NOT IN   
(SELECT ProductRef FROM GERMANDB.dbo.ITEMS where ACTIVE=1))  
) tb  
order by Priority, ProductRef