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1、创建三张测试表；

create table test_a(aid int,aname varchar(20));

create table test_b(bid int,bname varchar(20));

create table test_c(aid int, bid int,value varchar(20));

2、三张表e69da5e887aa3231313335323631343130323136353331333431376533中分别插入数据；

insert into test_a values(1, 'aname1');

insert into test_b values(2, 'bname1');

insert into test_c values(1, 2, 'cvalue');

3、查询表中记录；

select 10, a.* from test_a a

union all

select 20, b.* from test_b b

union all

select * from test_c c;

4、编写sql，进行三表关联；

select a.aname,b.bname,c.value

from test_c c join test_a a

on c.aid = a.aid

join test_b b

on c.bid = b.bid