MySQL 文档 声明:

MySQL 使用 Henry Spencer 的正则表达式实现，旨在符合 POSIX 1003.2.MySQL 使用扩展版本来支持在 SQL 语句中使用 REGEXP 运算符执行的模式匹配操作.

MySQL uses Henry Spencer's implementation of regular expressions, which is aimed at conformance with POSIX 1003.2. MySQL uses the extended version to support pattern-matching operations performed with the REGEXP operator in SQL statements.

好的，所以我们谈论的是 POSIX ERE.

Ok, so we're talking about POSIX ERE.

本页列出了各种正则表达式之间的详细信息，所以我会使用它作为备忘单.

This page lists the details between various regex flavors, so I'll use it as a cheatsheet.

1. ^[A-z\.]{3,36}

您正在使用:

• 锚点:^
• 字符类:[...]
• 范围量词:{n,m}

所有这些都在 POSIX ERE 中开箱即用，因此您可以按原样使用此表达式.但是转义字符类中的 . 是多余的，而 Az 在字符类中很可能是错误的(它包括 [\]^_\`)，所以只写:

All of these are supported out of the box in POSIX ERE, so you can use this expression as-is. But escaping the . in the character class is redundant, and A-z is most probably wrong in a character class (it includes [\]^_\`), so just write:

^[A-Za-z. ]{3,36}

^[a-z0-9.]{3,24}$

WHERE LENGTH(foo) >= 4
  AND foo REGEXP '[0-9]'
  AND foo REGEXP '[a-z]'
  AND foo REGEXP '[A-Z]'
  AND NOT foo REGEXP '[ \t\r\n]'