详解MySQL数据库中字符串的正确使用_MySQL
此文章主要介绍的是MySQL数据库的字符(串)的实际操作步骤，我们大家都知道MySQL数据库的字符(串)在实际操作是经常被用到了，所以你对其有更多的了解还是好的，希望会给你带来一些帮助在此方面。
MySQL数据库的字符(串)类不要以为字符类型就是CHAR，CHAR和VARCHAR的区别在于CHAR是固定长度，只要你定义一个字段是CHAR(10)，那么不论你存储的数据是否达到了10个字节，它都要占去10个字节的空间;而VARCHAR则是可变长度的，如果一个字段可能的值是不固定长度的，我们只知道它不可能超过10个字符，把它定义为VARCHAR(10)是最合算的，VARCHAR类型的占用空间是它的值的实际长度+1。
为什么要+1呢?这一个字节用于保存实际使用了多大的长度。从这个+1中也应该看到，如果一个字段，它的可能值最长是10个字符，而多数情况下也就是用到了10个字符时，用VARCHAR就不合算了：因为在多数情况下，实际占用空间是11个字节，比用CHAR(10)还多占用一个字节。
举个例子，就是一个存储股票名称和代码的表，股票名称绝大部分是四个字的，即8个字节;股票代码，上海的是六位数字，深圳的是四位数字。这些都是固定长度的，股票名称当然要用CHAR(8);股票代码虽然是不固定长度，但如果使用VARCHAR(6)，一个深圳的股票代码实际占用空间是5个字节，而一个上海的股票代码要占用7个字节!考虑到上海的股票数目比深圳的多，那么用VARCHAR(6)就不如CHAR(6)合算了。
虽然一个CHAR或VARCHAR的最大长度可以到255，我认为大于20的CHAR是几乎用不到的
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