db guideline
Merge pull request #7 from shjjia/master

database guideline
单列命名规范
Merge pull request #8 from enzhang/naming_convention

单列命名规范
example
整理 mysql guideline 的格式
add how to storage IP address.
fix style problem
format example.
Merge pull request #9 from zhiwensun/ip_address

增加保存IP地址相关
调整 IPv4 用法的措辞
调整条目的顺序
明确规范的适用范围为 OLTP 数据库
minor tweak
LIMIT 相关
Merge pull request #11 from enzhang/limit

LIMIT 相关
COUNT 相关
Merge pull request #10 from enzhang/count
minor format fix