2021-10-31 我的第一篇test
hello 我也开始写文章。打算以后把自己的错误总结到文章中,为后人避坑。
First of all, VARCHAR is not fixed length, but variable, so in general business development, we must try to use the smallest length to meet the needs, so as not to waste space and affect performance. Since it is a variable length, it must have a storage length. If the length of VARCHAR is set below 255, only one extra byte will be used to save the length, but if the length of VARCHAR is set above 255, then two extra bytes will be used to save the length, which is invisible In this way, storage space is wasted. ..., ,