黄东旭解析 TiDB 的核心优势
536
2023-05-30
*** 中的 ALL、SOME 和ANY
ALL、SOME 和 ANY是*** 三个比较运算符,其中 SOME 和 ANY 是等效的
SOME 或 ANY:当表达式与子查询返回的至少一个值比较时满足比较条件, SOME 或 ANY 就返回 TRUE。否则返回 FALSE
ALL :当表达式与子查询返回的所有值比较时满足比较条件, ALL 就返回 TRUE。否则返回 FALSE
create table test01 ( num int) insert into test01 select 5 union select 6 create table test02 (num int) insert into test02 select 2 union select 3 union select 6 union select 7 select * from test01
select * from test02
至此 test01 表中有数据: 5和 6 , test02表中有数据 :2,3,6,7
select num as num1 from test02 where num > all(select num from test01 ) select num as num2 from test02 where num > any(select num from test01 ) select num as num3 from test02 where num > some(select num from test01)
select num as num4 from test02 where num = all (select num from test01 ) select num as num5 from test02 where num = any(select num from test01 ) select num as num6 from test02 where num = some(select num from test01)
select num as num7 from test02 where num <> all (select num from test01 ) select num as num8 from test02 where num <> any (select num from test01 ) select num as num9 from test02 where num <>some(select num from test01)
从上面的测试结果看,= any 或 = some 与平时使用的 in 是等效的。
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