mysql 字符类以及重复元字符

字符类

[:alnum:]=[a-zA-Z0-]

[:alpha:]=[a-zA-Z]

[:digit:]=[-]

[:lower:]=[a-z]

[:upper:]=[A-Z]

[:xdigit:]=[a-fA-F0-]

重复元字符

* = >=
+ = >= = {,}
? = {,}

{n} 指定数目
{n,} = >=n
{n,m} = >=n and <=m