这个表(视图)是在MySQL5以后的才有的,现在MySQL4应该是很少了,所以都围绕着MySQL5来讲解，information_schema是用于存储数据库元数据的表，它保存了数据库名，表名，列名等信息，让我们从爆破表名到了可以直接查询。
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_LOCK_WAITS || INNODB_SYS_TABLESTATS || INNODB_CMP || INNODB_METRICS || INNODB_CMP_RESET || INNODB_CMP_PER_INDEX || INNODB_CMPMEM_RESET || INNODB_FT_DELETeD || INNODB_BUFFER_PAGE_LRU || INNODB_SYS_FOREIGN || INNODB_SYS_COLUMNS || INNODB_SYS_INDEXES || INNODB_FT_DEFAULT_STOPWORD || INNODB_SYS_FIELDS || INNODB_CMP_PER_INDEX_RESET || INNODB_BUFFER_PAGE || INNODB_CMPMEM || INNODB_FT_INDEX_TABLE || INNODB_FT_BEING_DELETED || INNODB_SYS_TABLESPACES || INNODB_FT_INDEX_CACHE || INNODB_SYS_FOREIGN_COLS || INNODB_SYS_TABLES || INNODB_BUFFER_POOL_STATS || INNODB_FT_ConFIG |+---------------------------------------+59 rows in set (0.00 sec)
我们经常用到的几个表
SCHEMATA表 ： 提供了当前mysql实例中所有数据库的信息。
TABLES 表 ： 提供了关于数据库中的表的信息。
COLUMNS 表 ：提供了表中的列信息
SCHEMATA:
mysql> select * from information_schema.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 | mysqltest | latin1 | latin1_swedish_ci | NULL || def | performance_schema | utf8 | utf8_general_ci | NULL |+--------------+--------------------+----------------------------+------------------------+----------+4 rows in set (0.00 sec)
TABLES:
mysql> select table_name from information_schema.tables where table_schema=0x6D7973716C74657374; //注意这里不用引号就要把数据库名转为16进制+------------+| table_name |+------------+| admin |+------------+1 row in set (0.00 sec)
COLUMNS：
mysql> select column_name from information_schema.columns where table_name=0x61646D696E; +-------------+| column_name |+-------------+| id || username || password |+-------------+3 rows in set (0.00 sec)
我们前面说过information_schema储存的是所有数据库的信息,假如我的数据库 mysqltest1 mysqltest2 都存在admin表的话 它都会显示出来
mysql> select column_name from information_schema.columns where table_name=0x61646D696E;+-------------+| column_name |+-------------+| id || username || password || id || user || pass |+-------------+6 rows in set (0.00 sec)
所以要指定数据库
mysql> select column_name from information_schema.columns where table_name=0x61646D696E and table_schema=0x6D7973716C74657374;+-------------+| column_name |+-------------+| id || username || password |+-------------+3 rows in set (0.00 sec)
0x01 MySQLuser 表保存的用户密码 和host等等信息
mysql> select user,password from user;+------------------+-------------------------------------------+| user | password |+------------------+-------------------------------------------+| root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B || root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B || root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B || root | *81F5E21E35407D884A6CD4A731AEBFB6AF209E1B || debian-sys-maint | *764E40048679D21BBB07CB8DDD18465359DAB4CA |+------------------+-------------------------------------------+5 rows in set (0.00 sec)
0x02 文末 本文如有错误，请及时提醒，避免误导他人