mysql 的研究

drop PROCEDURE if EXISTS insert_a1;
delimiter;;
create PROCEDURE insert_a1()
BEGIN
DECLARE i int;
set i = 1;
while(i<5000) DO 
insert into a1(name,phone) VALUES(i,18218149622);
set i=i+1;
end WHILE;
end;;
delimiter;
call insert_a1();

explain SELECT * from a2 
LEFT JOIN a1 on a2.member_id = a1.id
LEFT JOIN a3 on a2.item_id = a3.id
LEFT JOIN a4 on a2.sku_id = a4.id
;

结果