如何在 sql 查询中替换 UNION

Question

我有一个 table: attb

------------------------------------------------
Id | Name | Code | Attribute | Amount 
------------------------------------------------
1  | AV   | 123  | Alpha     | 233
------------------------------------------------
2  | TV   | 122  | Beta      | 235
------------------------------------------------
3  | TV   | 123  | Gama      | 238
------------------------------------------------
4  | CD   | 122  | Beta      | 239
------------------------------------------------
5  | TP   | 122  | Beta      | 240
------------------------------------------------
6  | RX   | 123  | Alpha     | 241
------------------------------------------------

我查询为：

select id,name, code, attribute, amount
from attb
where code = 123 and attribute='Alpha'
UNION
select id,name, code, attribute, amount
from attb
where code = 122;

下面是return

---

Id | Name | Code | Attribute | Amount 
------------------------------------------------
1  | AV   | 123  | Alpha     | 233
------------------------------------------------
2  | TV   | 122  | Beta      | 235
------------------------------------------------
4  | CD   | 122  | Beta      | 239
------------------------------------------------
5  | TP   | 122  | Beta      | 240
------------------------------------------------
6  | RX   | 123  | Alpha     | 241
------------------------------------------------

有没有一种方法可以合并两个查询而不是使用 UNION 运算符？或者有更好的实现方式吗？

Answer 1

只需将两个 where 子句放入一个查询中即可：

select id,name, code, attribute, amount
from attb
where (code = 123 and attribute='Alpha') 
   or code = 122;

输出：

id  name  code  attribute  amount
1   AV    123   Alpha      233 
2   TV    122   Beta       235 
4   CD    122   Beta       239 
5   TP    122   Beta       240 
6   RX    123   Alpha      241 

SQLFiddle demo

Answer 2

很容易。只需使用 or.

select id,name, code, attribute, amount
from attb
where (code = 123 and attribute='Alpha') OR code = 122

Answer 3

试试这个。

select id,name, code, attribute, amount
    from attb
    where ((code = 123 and attribute='Alpha') or (code = 122))

Answer 4

select id,name, code, attribute, amount
from attb
where (code IN(122, 123) and attribute='Alpha') ;