MySQL之information_schema数据库详细讲解_Mysql_

 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)

 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)

 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)

 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) 

 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) 

 mysql> SHOW INDEX FROM szhuizhong.users; +-------+------------+---------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_ind
                
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