mysql字符串后接空格匹配的bug

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今天插数据到mysql的时候发现居然有个bug，而且官方还认为这是很正常的情况。

先贴官方原文：

https://dev.mysql.com/doc/refman/5.5/en/char.html

All MySQL collations are of type PADSPACE. This means that all CHAR, VARCHAR, and TEXT values in MySQL are compared without regard to any trailing spaces. “Comparison” in this context does not include the LIKE pattern-matching operator, for which trailing spaces are significant.

This is true for all MySQL versions, and is not affected by the server SQL mode.

For those cases where trailing pad characters are stripped or comparisons ignore them, if a column has an index that requires unique values, inserting into the column values that differ only in number of trailing pad characters will result in a duplicate-key error. For example, if a table contains 'a', an attempt to store 'a ' causes a duplicate-key error.

今天比较多事，改天继续写。