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问题描述
查询大表(> 150 万行)3 次还是将 3 个条件放在同一个查询中更好?示例 where 子句如下.有类似或更复杂的 where 子句.我的预感是将它们全部放在相同的 where 中.但需要社区的一些投入.提前致谢.
Is it better to query large table (> 1.5 million rows) 3 times or to put 3 condition in the same query? The sample where clause is below. There are similar or more complicated where clauses. My hunch is to put all of them in same where. But need some input from community. Thanks in advance.
where (a =1 or b=1) and (a=2 or b=3) and (c=1 or d=3)
推荐答案
单次访问数据库绝对更可取.确保为 a、b、c 和 d 列建立索引，你应该没问题.
A single trip to the database is definitely preferable. Make sure you index the a, b, c and d columns and you should be fine.
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