MYSQL：
show databases；
use test;
show tables;
随机抽取两条数据：
select * from emp order by rand() limit 2;
随机抽取某一作用域：
select id from emp order by rand() limit 1;
MYSQL：
show databases；
use test;
show tables;
随机抽取两条数据：
select * from emp order by rand() limit 2;
随机抽取某一作用域：
select id from emp order by rand() limit 1;