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MySQL之information_schema数据库详细讲解

程序员文章站 2022-03-16 11:47:57
1. 概述information_schema 数据库跟 performance_schema 一样,都是 mysql 自带的信息数据库。其中 performance_schema 用于性能分析,而...

1. 概述

information_schema 数据库跟 performance_schema 一样,都是 mysql 自带的信息数据库。其中 performance_schema 用于性能分析,而 information_schema 用于存储数据库元数据(关于数据的数据),例如数据库名、表名、列的数据类型、访问权限等。

information_schema 中的表实际上是视图,而不是基本表,因此,文件系统上没有与之相关的文件。

mysql> use information_schema;
reading table information for completion of table and column names
you can turn off this feature to get a quicker startup with -a

database changed
mysql> show tables;
+---------------------------------------+
| tables_in_information_schema          |
+---------------------------------------+
| character_sets                        |
| collations                            |
| collation_character_set_applicability |
| columns                               |
| column_privileges                     |
| engines                               |
| events                                |
| files                                 |
| global_status                         |
| global_variables                      |
| key_column_usage                      |
| optimizer_trace                       |
| 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_locks                          |
| innodb_trx                            |
| innodb_sys_datafiles                  |
| innodb_ft_config                      |
| innodb_sys_virtual                    |
| innodb_cmp                            |
| innodb_ft_being_deleted               |
| innodb_cmp_reset                      |
| innodb_cmp_per_index                  |
| innodb_cmpmem_reset                   |
| innodb_ft_deleted                     |
| innodb_buffer_page_lru                |
| innodb_lock_waits                     |
| innodb_temp_table_info                |
| innodb_sys_indexes                    |
| innodb_sys_tables                     |
| innodb_sys_fields                     |
| innodb_cmp_per_index_reset            |
| innodb_buffer_page                    |
| innodb_ft_default_stopword            |
| innodb_ft_index_table                 |
| innodb_ft_index_cache                 |
| innodb_sys_tablespaces                |
| innodb_metrics                        |
| innodb_sys_foreign_cols               |
| innodb_cmpmem                         |
| innodb_buffer_pool_stats              |
| innodb_sys_columns                    |
| innodb_sys_foreign                    |
| innodb_sys_tablestats                 |
+---------------------------------------+
61 rows in set (0.00 sec)

2. information_schema 库中常用的表

character_sets 表

提供了 mysql 可用字符集的信息。show character set; 命令从这个表获取结果。

mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| charset  | description                     | default collation   | maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | big5 traditional chinese        | big5_chinese_ci     |      2 |
| dec8     | dec west european               | dec8_swedish_ci     |      1 |
| cp850    | dos west european               | cp850_general_ci    |      1 |
...
| eucjpms  | ujis for windows japanese       | eucjpms_japanese_ci |      3 |
| gb18030  | china national standard gb18030 | gb18030_chinese_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.07 sec)

mysql> select * from character_sets;
+--------------------+----------------------+---------------------------------+--------+
| character_set_name | default_collate_name | description                     | maxlen |
+--------------------+----------------------+---------------------------------+--------+
| big5               | big5_chinese_ci      | big5 traditional chinese        |      2 |
| dec8               | dec8_swedish_ci      | dec west european               |      1 |
| cp850              | cp850_general_ci     | dos west european               |      1 |
...
| eucjpms            | eucjpms_japanese_ci  | ujis for windows japanese       |      3 |
| gb18030            | gb18030_chinese_ci   | china national standard gb18030 |      4 |
+--------------------+----------------------+---------------------------------+--------+
41 rows in set (0.00 sec)

schemata 表

当前 mysql 实例中所有数据库的信息。show databases; 命令从这个表获取数据。

mysql> select * from schemata;
+--------------+--------------------+----------------------------+------------------------+----------+
| catalog_name | schema_name        | default_character_set_name | default_collation_name | sql_path |
+--------------+--------------------+----------------------------+------------------------+----------+
| def          | information_schema | utf8                       | utf8_general_ci        | null     |
| def          | mysql              | latin1                     | latin1_swedish_ci      | null     |
| def          | performance_schema | utf8                       | utf8_general_ci        | null     |
| def          | sys                | utf8                       | utf8_general_ci        | null     |
| def          | test               | utf8                       | utf8_unicode_ci        | null     |
+--------------+--------------------+----------------------------+------------------------+----------+
10 rows in set (0.00 sec)

mysql> show databases;
+--------------------+
| database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| test               |
+--------------------+
10 rows in set (0.00 sec)

tables 表

存储数据库中的表信息(包括视图),包括表属于哪个数据库,表的类型、存储引擎、创建时间等信息。show tables from xx; 命令从这个表获取结果。

mysql> select * from tables;
+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+
| table_catalog | table_schema       | table_name                                           | table_type  | engine             | version | row_format | table_rows | avg_row_length | data_length | max_data_length    | index_length | data_free | auto_increment | create_time         | update_time         | check_time          | table_collation   | checksum | create_options     | table_comment                              |
+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+
| def           | information_schema | character_sets                                       | system view | memory             |      10 | fixed      |       null |            384 |           0 |           16434816 |            0 |         0 |           null | 2018-04-23 11:51:32 | null                | null                | utf8_general_ci   |     null | max_rows=43690     |                                            |
| def           | information_schema | collations                                           | system view | memory             |      10 | fixed      |       null |            231 |           0 |           16704765 |            0 |         0 |           null | 2018-04-23 11:51:32 | null                | null                | utf8_general_ci   |     null | max_rows=72628     |                                            |
...
| def           | zentao             | zt_usertpl                                           | base table  | myisam             |      10 | dynamic    |          0 |              0 |           0 |    281474976710655 |         1024 |         0 |              1 | 2017-08-16 16:36:45 | 2017-08-16 16:36:45 | null                | utf8_general_ci   |     null |                    |                                            |
+---------------+--------------------+------------------------------------------------------+-------------+--------------------+---------+------------+------------+----------------+-------------+--------------------+--------------+-----------+----------------+---------------------+---------------------+---------------------+-------------------+----------+--------------------+--------------------------------------------+
525 rows in set (3.03 sec)

mysql> show tables from zentao;
+-------------------+
| tables_in_zentao  |
+-------------------+
| zt_action         |
| zt_block          |
| zt_branch         |
...
| zt_usertpl        |
+-------------------+
48 rows in set (0.00 sec)

columns 表

存储表中的列信息,包括表有多少列、每个列的类型等。show columns from schemaname.tablename 命令从这个表获取结果。

mysql> select * from columns limit 2,5;
+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+
| table_catalog | table_schema       | table_name     | column_name        | ordinal_position | column_default | is_nullable | data_type | character_maximum_length | character_octet_length | numeric_precision | numeric_scale | datetime_precision | character_set_name | collation_name  | column_type | column_key | extra | privileges | column_comment | generation_expression |
+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+
| def           | information_schema | character_sets | description        |                3 |                | no          | varchar   |                       60 |                    180 |              null |          null |               null | utf8               | utf8_general_ci | varchar(60) |            |       | select     |                |                       |
| def           | information_schema | character_sets | maxlen             |                4 | 0              | no          | bigint    |                     null |                   null |                19 |             0 |               null | null               | null            | bigint(3)   |            |       | select     |                |                       |
| def           | information_schema | collations     | collation_name     |                1 |                | no          | varchar   |                       32 |                     96 |              null |          null |               null | utf8               | utf8_general_ci | varchar(32) |            |       | select     |                |                       |
| def           | information_schema | collations     | character_set_name |                2 |                | no          | varchar   |                       32 |                     96 |              null |          null |               null | utf8               | utf8_general_ci | varchar(32) |            |       | select     |                |                       |
| def           | information_schema | collations     | id                 |                3 | 0              | no          | bigint    |                     null |                   null |                19 |             0 |               null | null               | null            | bigint(11)  |            |       | select     |                |                       |
+---------------+--------------------+----------------+--------------------+------------------+----------------+-------------+-----------+--------------------------+------------------------+-------------------+---------------+--------------------+--------------------+-----------------+-------------+------------+-------+------------+----------------+-----------------------+
5 rows in set (0.08 sec)

statistics 表

表索引的信息。show index from schemaname.tablename; 命令从这个表获取结果。

mysql> show index from szhuizhong.users;
+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| table | non_unique | key_name      | seq_in_index | column_name | collation | cardinality | sub_part | packed | null | index_type | comment | index_comment |
+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| users |          0 | primary       |            1 | userid      | a         |        1460 |     null | null   |      | btree      |         |               |
| users |          0 | account_index |            1 | account     | a         |        1460 |     null | null   |      | btree      |         |               |
| users |          1 | corpid        |            1 | fromid      | a         |           2 |     null | null   | yes  | btree      |         |               |
+-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
3 rows in set (0.00 sec)

user_privileges 表

用户权限表。内容源自 mysql.user 授权表。是非标准表。

mysql> select * from user_privileges;
+-------------------------+---------------+-------------------------+--------------+
| grantee                 | table_catalog | privilege_type          | is_grantable |
+-------------------------+---------------+-------------------------+--------------+
| 'mysql.sys'@'localhost' | def           | usage                   | no           |
| 'root'@'%'              | def           | select                  | yes          |
| 'root'@'%'              | def           | insert                  | yes          |
| 'root'@'%'              | def           | update                  | yes          |
| 'root'@'%'              | def           | delete                  | yes          |
| 'root'@'%'              | def           | create                  | yes          |
| 'root'@'%'              | def           | drop                    | yes          |
| 'root'@'%'              | def           | reload                  | yes          |
| 'root'@'%'              | def           | shutdown                | yes          |
| 'root'@'%'              | def           | process                 | yes          |
| 'root'@'%'              | def           | file                    | yes          |
| 'root'@'%'              | def           | references              | yes          |
| 'root'@'%'              | def           | index                   | yes          |
| 'root'@'%'              | def           | alter                   | yes          |
| 'root'@'%'              | def           | show databases          | yes          |
| 'root'@'%'              | def           | super                   | yes          |
| 'root'@'%'              | def           | create temporary tables | yes          |
| 'root'@'%'              | def           | lock tables             | yes          |
| 'root'@'%'              | def           | execute                 | yes          |
| 'root'@'%'              | def           | replication slave       | yes          |
| 'root'@'%'              | def           | replication client      | yes          |
| 'root'@'%'              | def           | create view             | yes          |
| 'root'@'%'              | def           | show view               | yes          |
| 'root'@'%'              | def           | create routine          | yes          |
| 'root'@'%'              | def           | alter routine           | yes          |
| 'root'@'%'              | def           | create user             | yes          |
| 'root'@'%'              | def           | event                   | yes          |
| 'root'@'%'              | def           | trigger                 | yes          |
| 'root'@'%'              | def           | create tablespace       | yes          |
+-------------------------+---------------+-------------------------+--------------+
29 rows in set (0.00 sec)

schema_privileges 表

方案权限表。给出了关于方案(数据库)权限的信息。内容来自 mysql.db 授权表。是非标准表。

mysql> select * from schema_privileges;
+-------------------------+---------------+--------------+-------------------------+--------------+
| grantee                 | table_catalog | table_schema | privilege_type          | is_grantable |
+-------------------------+---------------+--------------+-------------------------+--------------+
| 'mysql.sys'@'localhost' | def           | sys          | trigger                 | no           |
| 'root'@'%'              | def           | mysql        | select                  | yes          |
| 'root'@'%'              | def           | mysql        | insert                  | yes          |
| 'root'@'%'              | def           | mysql        | update                  | yes          |
| 'root'@'%'              | def           | mysql        | delete                  | yes          |
| 'root'@'%'              | def           | mysql        | create                  | yes          |
| 'root'@'%'              | def           | mysql        | drop                    | yes          |
| 'root'@'%'              | def           | mysql        | references              | yes          |
| 'root'@'%'              | def           | mysql        | index                   | yes          |
| 'root'@'%'              | def           | mysql        | alter                   | yes          |
| 'root'@'%'              | def           | mysql        | create temporary tables | yes          |
| 'root'@'%'              | def           | mysql        | lock tables             | yes          |
| 'root'@'%'              | def           | mysql        | execute                 | yes          |
| 'root'@'%'              | def           | mysql        | create view             | yes          |
| 'root'@'%'              | def           | mysql        | show view               | yes          |
| 'root'@'%'              | def           | mysql        | create routine          | yes          |
| 'root'@'%'              | def           | mysql        | alter routine           | yes          |
| 'root'@'%'              | def           | mysql        | event                   | yes          |
| 'root'@'%'              | def           | mysql        | trigger                 | yes          |
+-------------------------+---------------+--------------+-------------------------+--------------+
19 rows in set (0.00 sec)

table_privileges 表

表权限表。给出了关于表权限的信息。内容源自 mysql.tables_priv 授权表。是非标准表。

mysql> select * from table_privileges;
+-------------------------+---------------+--------------+------------+----------------+--------------+
| grantee                 | table_catalog | table_schema | table_name | privilege_type | is_grantable |
+-------------------------+---------------+--------------+------------+----------------+--------------+
| 'mysql.sys'@'localhost' | def           | sys          | sys_config | select         | no           |
+-------------------------+---------------+--------------+------------+----------------+--------------+
1 row in set (0.00 sec)

column_privileges 表

列权限表。给出了关于列权限的信息。内容源自 mysql.columns_priv 授权表。是非标准表。

mysql> select * from column_privileges;
empty set (0.00 sec)

collations 表

提供了关于各字符集的对照信息。show collation; 命令从这个表获取结果。

mysql> select * from collations;
+--------------------------+--------------------+-----+------------+-------------+---------+
| collation_name           | character_set_name | id  | is_default | is_compiled | sortlen |
+--------------------------+--------------------+-----+------------+-------------+---------+
| big5_chinese_ci          | big5               |   1 | yes        | yes         |       1 |
| big5_bin                 | big5               |  84 |            | yes         |       1 |
| dec8_swedish_ci          | dec8               |   3 | yes        | yes         |       1 |
| dec8_bin                 | dec8               |  69 |            | yes         |       1 |
...
| gb18030_bin              | gb18030            | 249 |            | yes         |       1 |
| gb18030_unicode_520_ci   | gb18030            | 250 |            | yes         |       8 |
+--------------------------+--------------------+-----+------------+-------------+---------+
222 rows in set (0.03 sec)

collation_character_set_applicability 表

指明了可用于校对的字符集。相当于 show collation 命令结果的前两个字段。

mysql> select * from collation_character_set_applicability;
+--------------------------+--------------------+
| collation_name           | character_set_name |
+--------------------------+--------------------+
| big5_chinese_ci          | big5               |
| big5_bin                 | big5               |
| dec8_swedish_ci          | dec8               |
...
| gb18030_bin              | gb18030            |
| gb18030_unicode_520_ci   | gb18030            |
+--------------------------+--------------------+
222 rows in set (0.00 sec)

table_constraints 表

描述了存在约束的表。以及表的约束类型。

mysql> select * from table_constraints;
+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+
| constraint_catalog | constraint_schema | constraint_name    | table_schema | table_name                | constraint_type |
+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+
| def                | mysql             | primary            | mysql        | columns_priv              | primary key     |
| def                | mysql             | primary            | mysql        | db                        | primary key     |
| def                | mysql             | primary            | mysql        | engine_cost               | primary key     |
| def                | mysql             | primary            | mysql        | event                     | primary key     |
| def                | mysql             | primary            | mysql        | func                      | primary key     |
| def                | mysql             | primary            | mysql        | gtid_executed             | primary key     |
| def                | mysql             | primary            | mysql        | help_category             | primary key     |
| def                | mysql             | name               | mysql        | help_category             | unique          |
| def                | mysql             | primary            | mysql        | help_keyword              | primary key     |
| def                | mysql             | name               | mysql        | help_keyword              | unique          |
| def                | mysql             | primary            | mysql        | help_relation             | primary key     |
| def                | mysql             | primary            | mysql        | help_topic                | primary key     |
| def                | mysql             | name               | mysql        | help_topic                | unique          |
| def                | mysql             | primary            | mysql        | innodb_index_stats        | primary key     |
| def                | mysql             | primary            | mysql        | innodb_table_stats        | primary key     |
| def                | mysql             | primary            | mysql        | ndb_binlog_index          | primary key     |
| def                | mysql             | primary            | mysql        | plugin                    | primary key     |
| def                | mysql             | primary            | mysql        | proc                      | primary key     |
| def                | mysql             | primary            | mysql        | procs_priv                | primary key     |
| def                | mysql             | primary            | mysql        | proxies_priv              | primary key     |
| def                | mysql             | primary            | mysql        | server_cost               | primary key     |
| def                | mysql             | primary            | mysql        | servers                   | primary key     |
| def                | mysql             | primary            | mysql        | slave_master_info         | primary key     |
| def                | mysql             | primary            | mysql        | slave_relay_log_info      | primary key     |
| def                | mysql             | primary            | mysql        | slave_worker_info         | primary key     |
| def                | mysql             | primary            | mysql        | tables_priv               | primary key     |
| def                | mysql             | primary            | mysql        | time_zone                 | primary key     |
| def                | mysql             | primary            | mysql        | time_zone_leap_second     | primary key     |
| def                | mysql             | primary            | mysql        | time_zone_name            | primary key     |
| def                | mysql             | primary            | mysql        | time_zone_transition      | primary key     |
| def                | mysql             | primary            | mysql        | time_zone_transition_type | primary key     |
| def                | mysql             | primary            | mysql        | user                      | primary key     |
| def                | sys               | primary            | sys          | sys_config                | primary key     |
| def                | zentao            | primary            | zentao       | zt_action                 | primary key     |
...
| def                | zentao            | account            | zentao       | zt_usergroup              | unique          |
| def                | zentao            | primary            | zentao       | zt_userquery              | primary key     |
| def                | zentao            | primary            | zentao       | zt_usertpl                | primary key     |
+--------------------+-------------------+--------------------+--------------+---------------------------+-----------------+
213 rows in set (0.37 sec)

key_column_usage 表

描述了具有约束的键列。

mysql> select * from key_column_usage;
+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
| constraint_catalog | constraint_schema | constraint_name    | table_catalog | table_schema | table_name                | column_name        | ordinal_position | position_in_unique_constraint | referenced_table_schema | referenced_table_name | referenced_column_name |
+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
| def                | mysql             | primary            | def           | mysql        | columns_priv              | host               |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | columns_priv              | db                 |                2 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | columns_priv              | user               |                3 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | columns_priv              | table_name         |                4 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | columns_priv              | column_name        |                5 |                          null | null                    | null                  | null                   |
...
| def                | mysql             | primary            | def           | mysql        | time_zone_leap_second     | transition_time    |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | time_zone_name            | name               |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | time_zone_transition      | time_zone_id       |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | time_zone_transition      | transition_time    |                2 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | time_zone_transition_type | time_zone_id       |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | time_zone_transition_type | transition_type_id |                2 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | user                      | host               |                1 |                          null | null                    | null                  | null                   |
| def                | mysql             | primary            | def           | mysql        | user                      | user               |                2 |                          null | null                    | null                  | null                   |
| def                | sys               | primary            | def           | sys          | sys_config                | variable           |                1 |                          null | null                    | null                  | null                   |
+--------------------+-------------------+--------------------+---------------+--------------+---------------------------+--------------------+------------------+-------------------------------+-------------------------+-----------------------+------------------------+
278 rows in set (0.03 sec)

routines 表

提供了关于存储子程序(存储程序和函数)的信息。此时,routines 表不包含自定义函数(udf)。名为“mysql.proc name”的列指明了对应于 information_schema.routines 表的 mysql.proc 列。

views 表

给出了关于数据库中的视图的信息。需要有 show views 权限,否则无法查看视图信息。

mysql> select * from views limit 1\g
*************************** 1. row ***************************
       table_catalog: def
        table_schema: sys
          table_name: host_summary
     view_definition: select if(isnull(`performance_schema`.`accounts`.`host`),'background',`performance_schema`.`accounts`.`host`) as `host`,sum(`stmt`.`total`) as `statements`,`sys`.`format_time`(sum(`stmt`.`total_latency`)) as `statement_latency`,`sys`.`format_time`(ifnull((sum(`stmt`.`total_latency`) / nullif(sum(`stmt`.`total`),0)),0)) as `statement_avg_latency`,sum(`stmt`.`full_scans`) as `table_scans`,sum(`io`.`ios`) as `file_ios`,`sys`.`format_time`(sum(`io`.`io_latency`)) as `file_io_latency`,sum(`performance_schema`.`accounts`.`current_connections`) as `current_connections`,sum(`performance_schema`.`accounts`.`total_connections`) as `total_connections`,count(distinct `performance_schema`.`accounts`.`user`) as `unique_users`,`sys`.`format_bytes`(sum(`mem`.`current_allocated`)) as `current_memory`,`sys`.`format_bytes`(sum(`mem`.`total_allocated`)) as `total_memory_allocated` from (((`performance_schema`.`accounts` join `sys`.`x$host_summary_by_statement_latency` `stmt` on((`performance_schema`.`accounts`.`host` = `stmt`.`host`))) join `sys`.`x$host_summary_by_file_io` `io` on((`performance_schema`.`accounts`.`host` = `io`.`host`))) join `sys`.`x$memory_by_host_by_current_bytes` `mem` on((`performance_schema`.`accounts`.`host` = `mem`.`host`))) group by if(isnull(`performance_schema`.`accounts`.`host`),'background',`performance_schema`.`accounts`.`host`)
        check_option: none
        is_updatable: no
             definer: mysql.sys@localhost
       security_type: invoker
character_set_client: utf8
collation_connection: utf8_general_ci
1 row in set (0.03 sec)

triggers 表

提供了关于触发程序的信息。必须有 super 权限才能查看该表。

mysql> select * from triggers limit 1\g
*************************** 1. row ***************************
           trigger_catalog: def
            trigger_schema: sys
              trigger_name: sys_config_insert_set_user
        event_manipulation: insert
      event_object_catalog: def
       event_object_schema: sys
        event_object_table: sys_config
              action_order: 1
          action_condition: null
          action_statement: begin if @sys.ignore_sys_config_triggers != true and new.set_by is null then set new.set_by = user(); end if; end
        action_orientation: row
             action_timing: before
action_reference_old_table: null
action_reference_new_table: null
  action_reference_old_row: old
  action_reference_new_row: new
                   created: 2017-05-27 11:18:43.60
                  sql_mode: 
                   definer: mysql.sys@localhost
      character_set_client: utf8
      collation_connection: utf8_general_ci
        database_collation: utf8_general_ci
1 row in set (0.00 sec)

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