Mysql 使用临时表比较数据差异以及 临时表的优化

-- 创建内存级别带索引的临时表
CREATE TEMPORARY TABLE ‘atest‘(
‘id‘ int(11) NOT NULL AUTO_INCREMENT,
‘pid‘ bigint(20) Default 0,
‘sid‘ bigint(20) Default 0,
KEY ‘index_pid‘ (‘pid‘),
KEY ‘index_sid‘ (‘sid‘)
)  ENGINE =MEMORY DEFAULT CHARSET=utf8;


CREATE TEMPORARY TABLE ‘btest‘(
‘pid‘ bigint(20) Default 0,
‘sid‘ bigint(20) Default 0,
KEY ‘index_pid‘ (‘pid‘),
KEY ‘index_sid‘ (‘sid‘)
)  ENGINE =MEMORY DEFAULT CHARSET=utf8;

insert into atest select id ,pid ,sid from tb_parent_student;
insert into btest select pid ,sid from  tb_child join tb_parent on pid=pid;

-- 使用普通方式创建默认临时表方法
create temporary table atest(select id ,pid ,sid from tb_parent_student);
create temporary table btest(select pid ,sid from  tb_child join tb_parent on pid=pid);

select *From atest;
select *From btest;

-- Exists 比较两个结果集的差异信息
select *From atest where not Exists (select *From btest where atest.pid=btest.pid and atest.sid=btest.sid);

select *From btest where not Exists (select *from atest where atest.pid=btest.pid and atest.sid=btest.sid);
-- left join 
select *From atest m 
left join btest as a 
on m.pid=a.pid and m.sid=a.sid;

select *From atest m 
left join btest as a 
on m.pid=a.pid and m.sid=a.sid;