摘要：
1、EXPLAIN (SELECT * FROM m_news WHERE TYPES = 5 )UNION (SELECT * FROM m_news WHERE TYPES = 10 );2、EXPLAIN SELECT * FROM m_news WHERE TYPES = 5 OR TYPES =10;3、EXPLAIN SELECT * FROM m_news WHERE TYPES IN (5,10);结论：从影响行数来说，用'or'和‘in’ 效果是一样的，‘union’效率高很多。 阅读全文
