我只是不明白一件事。当我输入：
SELECT table_name FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE';
我明白了：
+----------------------------------------------+
| table_name |
+----------------------------------------------+
| columns_priv |
| db |
| event |
| func |
| general_log |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| host |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| servers |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
| cond_instances |
| events_waits_current |
| events_waits_history |
| events_waits_history_long |
| events_waits_summary_by_instance |
| events_waits_summary_by_thread_by_event_name |
| events_waits_summary_global_by_event_name |
| file_instances |
| file_summary_by_event_name |
| file_summary_by_instance |
| mutex_instances |
| performance_timers |
| rwlock_instances |
| setup_consumers |
| setup_instruments |
| setup_timers |
| threads |
+----------------------------------------------+
41 rows in set (0.23 sec)
但选择似乎根本不起作用：
mysql> select * from db;
ERROR 1109 (42S02): Unknown table 'db' in information_schema
mysql>
怎么可能？我的意思是，SELECT table_name FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE';表明有一个名为'db'的表......
其次，当我输入：SELECT table_name FROM INFORMATION_SCHEMA.TABLES;时，它会给我：
+----------------------------------------------+
| table_name |
+----------------------------------------------+
| CHARACTER_SETS |
| COLLATIONS |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS |
| COLUMN_PRIVILEGES |
| ENGINES |
| EVENTS |
| FILES |
| GLOBAL_STATUS |
| GLOBAL_VARIABLES |
| KEY_COLUMN_USAGE |
| PARAMETERS |
| PARTITIONS |
| PLUGINS |
| PROCESSLIST |
| PROFILING |
| REFERENTIAL_CONSTRAINTS |
| ROUTINES |
| SCHEMATA |
| SCHEMA_PRIVILEGES |
| SESSION_STATUS |
| SESSION_VARIABLES |
| STATISTICS |
| TABLES |
| TABLESPACES |
| TABLE_CONSTRAINTS |
| TABLE_PRIVILEGES |
| TRIGGERS |
| USER_PRIVILEGES |
| VIEWS |
| INNODB_BUFFER_PAGE |
| INNODB_TRX |
| INNODB_BUFFER_POOL_STATS |
| INNODB_LOCK_WAITS |
| INNODB_CMPMEM |
| INNODB_CMP |
| INNODB_LOCKS |
| INNODB_CMPMEM_RESET |
| INNODB_CMP_RESET |
| INNODB_BUFFER_PAGE_LRU |
| columns_priv |
| db |
| event |
| func |
| general_log |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| host |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| servers |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
| cond_instances |
| events_waits_current |
| events_waits_history |
| events_waits_history_long |
| events_waits_summary_by_instance |
| events_waits_summary_by_thread_by_event_name |
| events_waits_summary_global_by_event_name |
| file_instances |
| file_summary_by_event_name |
| file_summary_by_instance |
| mutex_instances |
| performance_timers |
| rwlock_instances |
| setup_consumers |
| setup_instruments |
| setup_timers |
| threads |
+----------------------------------------------+
81 rows in set (0.00 sec)
我能做：mysql> select * from events;我得到了一些结果。这是为什么？为什么我只能选择大写字母？而且，我如何选择仅以大写字母表示的information_schema表格？干杯
如果重要：我以root身份登录到我的数据库。
答案 0 :(得分：3)
您只选择table_name，但是table_schema：
MariaDB [(none)]> SELECT table_name, table_schema FROM INFORMATION_SCHEMA.TABLES WHERE
TABLE_TYPE = 'BASE TABLE';
+----------------------------------------------+--------------------+
| table_name | table_schema |
+----------------------------------------------+--------------------+
| columns_priv | mysql |
| db | mysql |
| event | mysql |
| func | mysql |
| general_log | mysql |
| help_category | mysql |
| help_keyword | mysql |
| help_relation | mysql |
| help_topic | mysql |
| host | mysql |
| ndb_binlog_index | mysql |
| plugin | mysql |
| proc | mysql |
| procs_priv | mysql |
| proxies_priv | mysql |
| servers | mysql |
| slow_log | mysql |
| tables_priv | mysql |
| time_zone | mysql |
| time_zone_leap_second | mysql |
| time_zone_name | mysql |
| time_zone_transition | mysql |
| time_zone_transition_type | mysql |
| user | mysql |
| cond_instances | performance_schema |
| events_waits_current | performance_schema |
| events_waits_history | performance_schema |
| events_waits_history_long | performance_schema |
| events_waits_summary_by_instance | performance_schema |
| events_waits_summary_by_thread_by_event_name | performance_schema |
| events_waits_summary_global_by_event_name | performance_schema |
| file_instances | performance_schema |
| file_summary_by_event_name | performance_schema |
| file_summary_by_instance | performance_schema |
| mutex_instances | performance_schema |
| performance_timers | performance_schema |
| rwlock_instances | performance_schema |
| setup_consumers | performance_schema |
| setup_instruments | performance_schema |
| setup_timers | performance_schema |
| threads | performance_schema |
+----------------------------------------------+--------------------+
你得到：
MariaDB [(none)]> select * from mysql.db;
Empty set (0.00 sec)
答案 1 :(得分：2)
'information_schema'只有服务信息。它有关于表'db'存在的信息，但它表'不是'information_schema'数据库 - 某处，而不是'information_schema'。
有关需要在TABLE_SCHEMA字段中保存的表的数据库的信息