MySQL如何返回这两个查询的UNION？

Question

你如何获得这两个查询的UNION：

SELECT DOM，子FROM表WHERE table.dom = x或table.sub = X

SELECT DOM，子FROM表WHERE table.dom = Y OR table.sub = Y

dom和sub是整数，两个查询都返回一组整数，那么如何获得这两组的集合？

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Answer 1

你使用UNION有了答案，但为什么不只是

SELECT dom,sub FROM table 
    WHERE table.dom = X OR table.sub = X OR table.dom = Y OR table.sub = Y 

或

SELECT dom,sub FROM table 
    WHERE table.dom in (X,Y) OR table.sub in (X,Y) 

（假设你是ind在两个查询中谈论同一张表）？

Answer 2

SELECT dom,sub FROM table WHERE table.dom = X OR table.sub = X 
UNION 
SELECT dom,sub FROM table WHERE table.dom = Y OR table.sub = Y 

...

Answer 3

下面的查询将删除类似记录，即只显示不同

SELECT dom,sub FROM table WHERE table.dom = X OR table.sub = X 
UNION 
SELECT dom,sub FROM table WHERE table.dom = Y OR table.sub = Y 

如果你希望所有的记录，使用

SELECT dom,sub FROM table WHERE table.dom = X OR table.sub = X 
UNION ALL 
SELECT dom,sub FROM table WHERE table.dom = Y OR table.sub = Y