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oracle取差值集合

Oracle Minus关键字
SQL中的MINUS关键字
SQL中有一个MINUS关键字,它运用在两个SQL语句上,它先找出第一条SQL语句所产生的结果,然后看这些结果有没有在第二个SQL语句的结果中。如果有的话,那这一笔记录就被去除,而不会在最后的结果中出现。如果第二个SQL语句所产生的结果并没有存在于第一个SQL语句所产生的结果内,那这笔资料就被抛弃,其语法如下:
[SQL Segment 1]
MINUS
[SQL Segment 2]
--------------------------------------------
//创建表1

create table test1(name varchar(10),sex varchar(10),);insert into test1 values(test,female);insert into test1 values(test1,female);insert into test1 values(test1,female);insert into test1 values(test11,female);insert into test1 values(test111,female);


//创建表2

create table test2(name varchar(10),sex varchar(10),);insert into test1 values(test,female);insert into test1 values(test2,female);insert into test1 values(test2,female);insert into test1 values(test22,female);insert into test1 values(test222,female);

-------------------------------------------

select * from test1 minus select * from test2;结果:NAME SEX ---------- ---------- test1 female test11 female test111 female -----------------------------------------------------------select * from test2 minus select * from test1;结果:NAME SEX ---------- ---------- test2 female test22 female test222 female

结论:Minus返回的总是左边表中的数据,它返回的是差集。注意:minus有剃重作用

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下面是我做的实验,很明显能够看出MINUS的效率,made_order共23万笔记录,charge_detail共17万笔记录

性能比较:

SELECT order_id FROM made_order  MINUS  SELECT order_id FROM charge_detail  1.14 sec  SELECT a.order_id FROM made_order a  WHERE NOT exists (   SELECT order_id   FROM charge_detail   WHERE order_id = a.order_id   )  18.19 sec  SELECT order_id FROM made_order  WHERE order_id NOT in (   SELECT order_id   FROM charge_detail   )  20.05 sec

还有其它一下关键字:
INTERSECT (交集)
UNION ALL 并集

oracle取差值集合