mysql数据库 用例：mysql 

mysql> show tables;

+---------------------------+

| Tables_in_mysql           |

+---------------------------+

| columns_priv              |

| db                        |

| event                     |

| func                      |

| general_log               |

| help_category             |

| help_keyword              |

| help_relation             |

| help_topic                |

| innodb_index_stats        |

| innodb_table_stats        |

| ndb_binlog_index          |

| plugin                    |

| proc                      |

| procs_priv                |

| proxies_priv              |

| servers                   |

| slave_master_info         |

| slave_relay_log_info      |

| slave_worker_info         |

| slow_log                  |

| tables_priv               |

| time_zone                 |

| time_zone_leap_second     |

| time_zone_name            |

| time_zone_transition      |

| time_zone_transition_type |

| user                      |

+---------------------------+

28 rows in set (0.01 sec)

SELECT

  t.TABLE_NAME,

  t.CONSTRAINT_TYPE,

  c.COLUMN_NAME,

  c.ORDINAL_POSITION

FROM

  INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS t,

  INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS c

WHERE

  t.TABLE_NAME = c.TABLE_NAME

  -- AND t.TABLE_SCHEMA = 数据库名称

  AND t.CONSTRAINT_TYPE = 'PRIMARY KEY' and c.TABLE_NAME='user';

1、服务器防护墙开着

2、user表问题 将user='' host=''

解决办法：

1、关闭防护墙

2、删除user='' and host=''记录