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SqlServer 优化技巧
2020-05-20 【后端开发】 1566人已围观 3033次浏览
简介SqlServer 优化技巧
查询在A表但是不在B表中的数据
– 效率低,但是容易理解
select distinct A.ID from A where A.ID not in (select ID from B)
– 图解
select A.ID from A left join B on A.ID=B.ID where B.ID is null
– 逻辑相对复杂,但是效率最高
select * from B where (select count(1) as num from A where A.ID = B.ID) = 0
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