PHP+MySQL开发的网站注入时主要针对information_schema这个数据库进行的它是你用php+mysql开发网站自动形成的数据库里面存了很多信息
schemata：存了所有数据库的名字tables：所有表的名字columns：字段的名字以下是该数据库的所有表
+---------------------------------------+
| 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 |
+---------------------------------------+show tables和describe tables的结果不同
后一个是显示出表结构
select tables_name from information_schema.tables where table_schema="test";
意思是从数据库information_schema中选取其中表
表名叫tables_name，表中某个字段名叫table_schema
该字段的值是test
