MySQL INFORMATION_SCHEMA database introduction:

1, character_sets table create temporary table ' character_sets ' (' character_set_name ' varchar ( +) Not NULL DEFAULT"', the name of the character set, such as set names UTF8; ' default_collate_name ' varchar ( +) Not NULL DEFAULT"', the full name of the character set ' DESCRIPTION ' varchar ( -) Not NULL DEFAULT"', the description of the field ' MaxLen ' bigint (3) Not NULL DEFAULT'0'the length of the character set, for example UTF8 is 3 bytes) ENGINE=memory DEFAULT charset=The UTF8 is stored in a MySQL-supported character set. 2, COLUMNS table, stores all column information create temporary table ' COLUMNS ' (' table_catalog ' varchar ( +) Not NULL DEFAULT"', ' table_schema ' varchar ( -) Not NULL DEFAULT"', database name ' table_name ' varchar ( -) Not NULL DEFAULT"', table name ' column_name ' varchar ( -) Not NULL DEFAULT"', column name ' Ordinal_position ' bigint ( +) Unsigned not NULL DEFAULT'0', ' Column_default ' longtext, ' is_nullable ' varchar (3) Not NULL DEFAULT"', whether it is a null ' data_type ' varchar ( -) Not NULL DEFAULT"', field data type ' Character_maximum_length ' bigint ( +) unsigned DEFAULT NULL, ' character_octet_length ' bigint ( +) unsigned DEFAULT NULL, ' numeric_precision ' bigint ( +) unsigned DEFAULT NULL, ' Numeric_scale ' bigint ( +) unsigned DEFAULT NULL, ' datetime_precision ' bigint ( +) unsigned DEFAULT NULL, ' character_set_name ' varchar ( +) DEFAULT NULL, the encoding of the field ' collation_name ' varchar ( +) DEFAULT NULL, the full name of the encoded ' Column_type ' longtext not NULL, field-specific type ' column_key ' varchar (3) Not NULL DEFAULT"', ' EXTRA ' varchar ( -) Not NULL DEFAULT"', ' privileges ' varchar ( the) Not NULL DEFAULT"', you can perform operations on the field, such as select,insert,update ' column_comment ' varchar (1024x768) Not NULL DEFAULT"'field of your notes) ENGINE=myisam DEFAULT charset=UTF8 records information about all the fields inside each table3, ENGINES, Database engine table create temporary table ' ENGINES ' (' engine ' varchar ( -) Not NULL DEFAULT"', the database engine name ' support ' varchar (8) Not NULL DEFAULT"', does it support ' COMMENT ' varchar ( the) Not NULL DEFAULT"', annotated ' transactions ' varchar (3DEFAULT NULL, whether to support the thing ' XA ' varchar (3) DEFAULT NULL, whether XA distributed things ' savepoints ' varchar is supported (3) DEFAULT NULL) ENGINE=memory DEFAULT charset=UTF8 stored the data to the engine support situation4, the Global_status table, which stores some global states, is the source of the show status results. CREATE temporary TABLE ' global_status ' (' variable_name ' varchar (as opposed to session level) -) Not NULL DEFAULT"', variable name ' variable_value ' varchar (2048default NULL variable value) ENGINE=memory DEFAULT charset=UTF8 can query some of the database related states. 5, Global_variables table, global variable name table (relative to session level) CREATE temporary table ' global_variables ' (' variable_name ' varchar (  -) Not NULL DEFAULT"', variable name ' variable_value ' varchar (2048default NULL variable value) ENGINE=memory DEFAULT charset=UTF8 stores the variables of the database, the MySQL client's setGlobalVariabe, is the operation of this table6, Processlist table, current process table, show processlist data source create temporary table ' processlist ' (' ID ' bigint ( +) Unsigned not NULL DEFAULT'0', ' USER ' varchar ( -) Not NULL DEFAULT"', the user name of the connection ' HOST ' varchar ( -) Not NULL DEFAULT"', host address and Port ' DB ' varchar ( -) DEFAULT NULL, connected database ' COMMAND ' varchar ( -) Not NULL DEFAULT"', execute the command ' time 'int(7) Not NULL DEFAULT'0', time-consuming ' state ' varchar ( -) DEFAULT NULL, State ' info ' longtext, information ' Time_ms ' bigint ( +) Not NULL DEFAULT'0', ' rows_sent ' bigint ( +) Unsigned not NULL DEFAULT'0', ' rows_examined ' bigint ( +) Unsigned not NULL DEFAULT'0') ENGINE=myisam DEFAULT charset=UTF87, PROFILING table, Performance profile table for SQL statements, such as executing a SELECT statement, some column information returned by the client create temporary table ' PROFILING ' (' query_id 'int( -) Not NULL DEFAULT'0', ' SEQ 'int( -) Not NULL DEFAULT'0', ' state ' varchar ( -) Not NULL DEFAULT"', ' DURATION 'decimal(9,6) Not NULL DEFAULT'0.000000', ' Cpu_user 'decimal(9,6) DEFAULT NULL, ' Cpu_system 'decimal(9,6) DEFAULT NULL, ' context_voluntary 'int( -) DEFAULT NULL, ' context_involuntary 'int( -) DEFAULT NULL, ' block_ops_in 'int( -) DEFAULT NULL, ' block_ops_out 'int( -) DEFAULT NULL, ' messages_sent 'int( -) DEFAULT NULL, ' messages_received 'int( -) DEFAULT NULL, ' page_faults_major 'int( -) DEFAULT NULL, ' Page_faults_minor 'int( -) DEFAULT NULL, ' SWAPS 'int( -) DEFAULT NULL, ' source_function ' varchar ( -) DEFAULT NULL, ' source_file ' varchar ( -) DEFAULT NULL, ' Source_line 'int( -) DEFAULT NULL) ENGINE=memory DEFAULT charset=UTF88, schema_privileges Database Permissions table, which records what permissions the account has on the data create temporary table ' schema_privileges ' (' GRANTEE ' varchar (Bayi) Not NULL DEFAULT"', the user @host ' table_catalog ' varchar ( +) Not NULL DEFAULT"', ' table_schema ' varchar ( -) Not NULL DEFAULT"', database name ' privilege_type ' varchar ( -) Not NULL DEFAULT"', permissions, such as insert ' is_grantable ' varchar (3) Not NULL DEFAULT"') ENGINE=memory DEFAULT charset=UTF89, Session_status,session_variables, with the upper Global_status,global_variables, is the SESSION-level variableTen, Statistics table, statistics about the index. CREATE temporary TABLE ' STATISTICS ' (' table_catalog ' varchar ( +) Not NULL DEFAULT"', ' table_schema ' varchar ( -) Not NULL DEFAULT"', database ' table_name ' varchar ( -) Not NULL DEFAULT"', table name ' Non_unique ' bigint (1) Not NULL DEFAULT'0', whether a unique index, 0 means yes, 1 is not ' index_schema ' varchar ( -) Not NULL DEFAULT"', ' index_name ' varchar ( -) Not NULL DEFAULT"', index name ' Seq_in_index ' bigint (2) Not NULL DEFAULT'0', ' column_name ' varchar ( -) Not NULL DEFAULT"', column name ' COLLATION ' varchar (1) DEFAULT NULL, ' cardinality ' bigint ( +) DEFAULT NULL, ' Sub_part ' bigint (3) DEFAULT NULL, ' PACKED ' varchar (Ten) DEFAULT NULL, ' NULLABLE ' varchar (3) Not NULL DEFAULT"', ' index_type ' varchar ( -) Not NULL DEFAULT"', index type, such as btree ' COMMENT ' varchar ( -) DEFAULT NULL, ' index_comment ' varchar (1024x768) Not NULL DEFAULT"') ENGINE=memory DEFAULT charset=UTF8 One, tables table, storage of table-related information. CREATE temporary TABLE ' TABLES ' (' table_catalog ' varchar ( +) Not NULL DEFAULT"', ' table_schema ' varchar ( -) Not NULL DEFAULT"', the database where the table resides ' table_name ' varchar ( -) Not NULL DEFAULT"', table name ' table_type ' varchar ( -) Not NULL DEFAULT"', ' ENGINE ' varchar ( -) DEFAULT NULL, table engine ' VERSION ' bigint ( +) unsigned DEFAULT NULL, ' row_format ' varchar ( -) DEFAULT NULL, ' table_rows ' bigint ( +) unsigned DEFAULT NULL, ' avg_row_length ' bigint ( +) unsigned DEFAULT NULL, ' data_length ' bigint ( +) unsigned DEFAULT NULL, ' max_data_length ' bigint ( +) unsigned DEFAULT NULL, ' index_length ' bigint ( +) unsigned DEFAULT NULL, ' Data_free ' bigint ( +) unsigned DEFAULT NULL, ' auto_increment ' bigint ( +) unsigned default null, ' Create_time ' datetime default NULL, ' Update_time ' datetime default NULL, ' Check_time ' dat ETime DEFAULT NULL, ' table_collation ' varchar ( +) DEFAULT NULL, ' CHECKSUM ' bigint ( +) unsigned DEFAULT NULL, ' create_options ' varchar (255) DEFAULT NULL, ' table_comment ' varchar (2048) Not NULL DEFAULT"') ENGINE=memory DEFAULT Charset=utf8


can be different in different beta environment, user diff database and table, resulting in SQL statements, synchronization database,
The next step is to write a script about the database table structure synchronization.

MySQL INFORMATION_SCHEMA database introduction: