为了使排序只适用于UNION中的第一个语句，你可以把它放在一个带有UNION ALL的子选择中(这两个在Oracle中都是必要的):

Select id,name,age FROM 
(    
 Select id,name,age
 From Student
 Where age < 15
 Order by name
)
UNION ALL
Select id,name,age
From Student
Where Name like "%a%"

或者(针对Nicholas Carey的评论)你可以保证顶部的SELECT是有序的，结果显示在下面的SELECT上面，就像这样:

Select id,name,age, 1 as rowOrder
From Student
Where age < 15
UNION
Select id,name,age, 2 as rowOrder
From Student
Where Name like "%a%"
Order by rowOrder, name

正如其他答案所述，在最后一个UNION之后的ORDER BY应该适用于由UNION连接的两个数据集。

我有两个使用不同表但相同列的数据集。上一个联盟之后的命令仍然没有起作用。

为ORDER BY子句中使用的列使用别名可以达到目的。

SELECT Name, Address FROM Employee 
UNION
SELECT Customer_Name, Address FROM Customer
ORDER BY customer_name;   --Won't work

解决方案是使用别名User_Name，如下所示:

SELECT Name AS User_Name, Address FROM Employee 
UNION
SELECT Customer_Name AS User_Name, Address FROM Customer
ORDER BY User_Name; 

为了使排序只适用于UNION中的第一个语句，你可以把它放在一个带有UNION ALL的子选择中(这两个在Oracle中都是必要的):

Select id,name,age FROM 
(    
 Select id,name,age
 From Student
 Where age < 15
 Order by name
)
UNION ALL
Select id,name,age
From Student
Where Name like "%a%"

或者(针对Nicholas Carey的评论)你可以保证顶部的SELECT是有序的，结果显示在下面的SELECT上面，就像这样:

Select id,name,age, 1 as rowOrder
From Student
Where age < 15
UNION
Select id,name,age, 2 as rowOrder
From Student
Where Name like "%a%"
Order by rowOrder, name

如果我希望排序只应用于一个UNION，请使用UNION ALL:

Select id,name,age
From Student
Where age < 15
Union all
Select id,name,age
From 
(
Select id,name,age
From Student
Where Name like "%a%"
Order by name
)

要将ORDER BY或LIMIT子句应用于单个SELECT，请将SELECT子句插入圆括号内:

(SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10)
UNION
(SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10);

顺序顺序应用在并集之后，所以 在语句的末尾添加一个order by子句:

Select id,name,age
From Student
Where age < 15
Union
Select id,name,age
From Student
Where Name like '%a%'
Order By name