MySQL经验教训

MySQL语句如下：

SELECT buyer_id FROM baoxian.bc_insurance_order WHERE id in (100000422,
100000418,
100000417,
100000416,
100000415,
100000413,
100000411,
100000410,
100000409,
100000408,
100000407,
100000406,
100000404,
100000403,
100000402,
100000399);

如此简单的SQL语句，可是SQL查出来结果居然是按id升序排列的！！！因此，写SQL语句一定要把查询条件也带出来，不然谁知道MySQL自作聪明的干了什么，WTF！！！

SELECT id, buyer_id FROM baoxian.bc_insurance_order WHERE id in (100000422,
100000418,
100000417,
100000416,
100000415,
100000413,
100000411,
100000410,
100000409,
100000408,
100000407,
100000406,
100000404,
100000403,
100000402,
100000399);

另外，mysql（5.7）中varchar长度是这样的，比如varchar(7)，则'http://'可以，‘一二三四五六七'也可以存，但'http://w'就超了，'一二三四五六七八'就超了。