Reference connection is not on the whole Baidu is the same. I have a comment about

# Comment comment; comments; criticism; Description

1, the new table and add the tables and fields of the annotations.
   Create Table T_USER (
        ID the INT (. 19) Primary Key AUTO_INCREMENT Comment 'master key',
        NAME VARCHAR (300) Comment 'name',
        CREATE_TIME DATE Comment 'Created'
    ) Comment = ' user information table ';

Add # field inherent field rearmost COMMENT Note, outside the parentheses by COMMENT = '' to add to the Notes to Table

2, the comment modify the table / field.
     　　ALTER Table T_USER Comment = 'table annotation information (user information table) modified';
    　　 alter table t_user modify column id int comment ' primary key ID';
   - Note: the field names and types according to the write line

. 3, details query the database for all tables (including comment table)
use INFORMATION_SCHEMA;
SELECT * from tABLES WHERE the TABLE_SCHEMA = 'database where your tables';
- a query of a table
use information_schema;
the SELECT * from the wHERE TABLE_SCHEMA tABLES = 'database tables where you' and TABLE_NAME = 'your table';

mysql> SELECT * FROM TABLES WHERE table_schema='test' AND table_name='test1'\G
*************************** 1. row ***************************
  TABLE_CATALOG: def
   TABLE_SCHEMA: test
     TABLE_NAME: test1
     TABLE_TYPE: BASE TABLE
         ENGINE: InnoDB
        VERSION: 10
     ROW_FORMAT: Dynamic
     TABLE_ROWS: 0
 AVG_ROW_LENGTH: 0
    DATA_LENGTH: 16384
MAX_DATA_LENGTH: 0
   INDEX_LENGTH: 0
      DATA_FREE: 0
 AUTO_INCREMENT: NULL
    CREATE_TIME: 2020-03-26 22:47:59
    UPDATE_TIME: NULL
     CHECK_TIME: NULL
TABLE_COLLATION: utf8_general_ci
       CHECKSUM: NULL
 CREATE_OPTIONS: 
  TABLE_COMMENT: Table I explain 
1 row in set (0.00 sec)

4, for more information query a table (including field notes, field name, type, etc.).
Use information_schema;
the SELECT * from information_schema.columns the WHERE table_schema = 'database tables where you' and table_name = 'your table' ;

mysql> mysql> SELECT * FROM COLUMNS WHERE table_schema='test' AND table_name='test1'\G
*************************** 1. row ***************************
           TABLE_CATALOG: def
            TABLE_SCHEMA: test
              TABLE_NAME: test1
             COLUMN_NAME: tt
        ORDINAL_POSITION: 1
          COLUMN_DEFAULT: NULL
             IS_NULLABLE: YES
               DATA_TYPE: int
CHARACTER_MAXIMUM_LENGTH: NULL
  CHARACTER_OCTET_LENGTH: NULL
       NUMERIC_PRECISION: 10
           NUMERIC_SCALE: 0
      DATETIME_PRECISION: NULL
      CHARACTER_SET_NAME: NULL
          COLLATION_NAME: NULL
             COLUMN_TYPE: int(11)
              COLUMN_KEY: 
                   EXTRA: 
              PRIVILEGES: select,insert,update,references
          COLUMN_COMMENT: 我是解释
   GENERATION_EXPRESSION: 
1 row in set (0.00 sec)

mysql>

Note: There is another way:

# View the construction of the table statement, you can see a table with the comments field Comment

show create table table_name;

MySQL> SHOW the CREATE TABLE test1 \ G 
*************************** 1. Row ************ *************** 
       the Table: test1 
the Create the Table: the CREATE TABLE `test1` ( 
  ` tt` int (11) the DEFAULT NULL the COMMENT 'I explain' 
) ENGINE = InnoDB the DEFAULT CHARSET = utf8 COMMENT = 'table I explain' 
1 Row in the SET (0.00 sec) 

MySQL>

# SHOW ways to view your comment field
show full columns from table name;

mysql> SHOW FULL COLUMNS FROM test1;
+-------+---------+-----------+------+-----+---------+-------+---------------------------------+--------------+
| Field | Type    | Collation | Null | Key | Default | Extra | Privileges                      | Comment      |
+-------+---------+-----------+------+-----+---------+-------+---------------------------------+--------------+
| tt    | int(11) | NULL      | YES  |     | NULL    |       | select,insert,update,references | 我是解释     |
+-------+---------+-----------+------+-----+---------+-------+---------------------------------+--------------+
1 row in set (0.00 sec)

mysql>

So Overall, we want to see if the information tables and fields, the best view of the statement by the construction of the table.

Is SHOW CREATE TABLE xxx, the most convenient