两张表关联删除：

DELETE a,b FROM table1 a
INNER JOIN  table2 b
ON a.id = b.aid
WHERE a.id = '1'
//或者也可以
DELETE a,b FROM table1 a,table2 b
WHERE a.id = b.aid
AND a.id = '1'

三张表删除

DELETE a,b,c FROM table1 a 
INNER JOIN  table2 b 
ON a.id = b.aid 
INNER JOIN table3 c 
ON a.id = c.aid 
WHERE a.id = '1'

不过这样有一个问题，就是如果a表里数据，而b表或者c表里没数据，那么整个删除就失败，即删除0条数据

如果你的主表一定有数据，而关联的表有可能有数据也有可能没数据的话，我们可以通过左连接删除的方式，把两张表都删除。无论关联的表有没有数据，主表都可以删除成功

DELETE a.* ,b.* ,c.*
FROM table1 a
LEFT JOIN table2 b
ON a.id = b.aid
LEFT JOIN table3 c
ON a.id = c.aid
WHERE a.id = 1