假设这category_id是表的索引键(不是主键)books.以下两个SQL语句之间有什么区别吗?
SELECT * FROM books WHERE author='Bill' AND category_id=1
SELECT * FROM books WHERE category_id=1 AND author='Bill'
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我想首先过滤记录category_id然后再author过滤比以相反顺序过滤它们更快.SQL引擎是否足够智能以这种方式实现?
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