select时找不到表：大小写问题

show variables like '%lower_case_table_names%';

使用help_topic时的select权限问题

Whitelabel Error PageThis application has no explicit mapping for /error, so you are seeing this as a fallback.Tue Aug 13 20:18:53 CST 2019There was an unexpected error (type=Internal Server Error, status=500).### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: SELECT command denied to user 'rpa'@'localhost' for table 'help_topic' ### The error may exist in ...

是因为mysql.help_topic表没有授权给用户'rpa'

localhost和127.0.0.1及%的问题

通过localhost连接到mysql是使用UNIX socket，而通过127.0.0.1连接到mysql是使用TCP/IP。