Mysql 中完善的帮助命令

Mysql 中完善的帮助命令

Mysql 中的帮助系统很完善，很多操作都可以通过命令行直接获得帮助，如下示例：

Mysql 命令行帮助

[root@mysql1 mydata1]# mysql -S /u01/mytmp/mysql.sock1
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 97
Server version: 8.0.16 MySQL Community Server - GPL
​
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
​
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
​
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
​
root@(none):35: >\h
​
For information about MySQL products and services, visit:
   http://www.mysql.com/
For developer information, including the MySQL Reference Manual, visit:
   http://dev.mysql.com/
To buy MySQL Enterprise support, training, or other products, visit:
   https://shop.mysql.com/
​
List of all MySQL commands:
Note that all text commands must be first on line and end with ';'
?         (\?) Synonym for `help'.
clear     (\c) Clear the current input statement.
connect   (\r) Reconnect to the server. Optional arguments are db and host.
delimiter (\d) Set statement delimiter.
edit      (\e) Edit command with $EDITOR.
ego       (\G) Send command to mysql server, display result vertically.
exit      (\q) Exit mysql. Same as quit.
go        (\g) Send command to mysql server.
help      (\h) Display this help.
nopager   (\n) Disable pager, print to stdout.
notee     (\t) Don't write into outfile.
pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.
print     (\p) Print current command.
prompt    (\R) Change your mysql prompt.
quit      (\q) Quit mysql.
rehash    (\#) Rebuild completion hash.
source    (\.) Execute an SQL script file. Takes a file name as an argument.
status    (\s) Get status information from the server.
system    (\!) Execute a system shell command.
tee       (\T) Set outfile [to_outfile]. Append everything into given outfile.
use       (\u) Use another database. Takes database name as argument.
charset   (\C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets.
warnings  (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.
resetconnection(\x) Clean session context.
​
For server side help, type 'help contents'

Mysql 帮助清单

root@(none):35: >select * from mysql.help_category;
+------------------+-----------------------------------------------+--------------------+-----+
| help_category_id | name                                          | parent_category_id | url |
+------------------+-----------------------------------------------+--------------------+-----+
|                1 | Account Management                            |                  7 |     |
|                2 | Administration                                |                  7 |     |
|                3 | Bit Functions                                 |                 14 |     |
|                4 | Comparison operators                          |                 14 |     |
|                5 | Components                                    |                  7 |     |
|                6 | Compound Statements                           |                  7 |     |
|                7 | Contents                                      |                  0 |     |
|                8 | Control flow functions                        |                 14 |     |
|                9 | Data Definition                               |                  7 |     |
|               10 | Data Manipulation                             |                  7 |     |
|               11 | Data Types                                    |                  7 |     |
|               12 | Date and Time Functions                       |                 14 |     |
|               13 | Encryption Functions                          |                 14 |     |
|               14 | Functions                                     |                  7 |     |
|               15 | Functions and Modifiers for Use with GROUP BY |                  7 |     |
|               16 | Geographic                                    |                  0 |     |
|               17 | Geographic Features                           |                  7 |     |
|               18 | Geometry constructors                         |                 17 |     |
|               19 | Geometry properties                           |                 17 |     |
|               20 | Geometry relations                            |                 17 |     |
|               21 | GeometryCollection properties                 |                 16 |     |
|               22 | Help Metadata                                 |                  7 |     |
|               23 | Information Functions                         |                 14 |     |
|               24 | Language Structure                            |                  7 |     |
|               25 | LineString properties                         |                 17 |     |
|               26 | Locking Functions                             |                 14 |     |
|               27 | Logical operators                             |                 14 |     |
|               28 | MBR                                           |                 17 |     |
|               29 | Miscellaneous Functions                       |                 14 |     |
|               30 | Numeric Functions                             |                 14 |     |
|               31 | Plugins                                       |                  7 |     |
|               32 | Point properties                              |                 17 |     |
|               33 | Polygon properties                            |                 17 |     |
|               34 | Storage Engines                               |                  7 |     |
|               35 | String Functions                              |                 14 |     |
|               36 | Table Maintenance                             |                  7 |     |
|               37 | Transactions                                  |                  7 |     |
|               38 | User-Defined Functions                        |                  7 |     |
|               39 | Utility                                       |                  7 |     |
|               40 | WKB                                           |                 17 |     |
|               41 | WKT                                           |                 17 |     |
+------------------+-----------------------------------------------+--------------------+-----+
41 rows in set (0.00 sec)

帮助案例

root@(none):38: >help Help Metadata
You asked for help about help category: "Help Metadata"
For more information, type 'help <item>', where <item> is one of the following
topics:
   HELP_DATE
   HELP_VERSION
​
root@(none):39: >help HELP_DATE
Name: 'HELP_DATE'
Description:
This help information was generated from the MySQL 8.0 Reference Manual
on: 2019-02-20
​
root@(none):39: >help HELP_VERSION
Name: 'HELP_VERSION'
Description:
This help information was generated from the MySQL 8.0 Reference Manual
on: 2019-02-20 (revision: 61006)
​
This information applies to MySQL 8.0 through 8.0.17.

查看支持的数据类型

root@(none):39: >help Data Types 
You asked for help about help category: "Data Types"
For more information, type 'help <item>', where <item> is one of the following
topics:
   AUTO_INCREMENT
   BIGINT
   BINARY
   BIT
   BLOB
   BLOB DATA TYPE
   BOOLEAN
   CHAR
   CHAR BYTE
   DATE
   DATETIME
   DEC
   DECIMAL
   DOUBLE
   DOUBLE PRECISION
   ENUM
   FLOAT
   INT
   INTEGER
   LONGBLOB
   LONGTEXT
   MEDIUMBLOB
   MEDIUMINT
   MEDIUMTEXT
   SET DATA TYPE
   SMALLINT
   TEXT
   TIME
   TIMESTAMP
   TINYBLOB
   TINYINT
   TINYTEXT
   VARBINARY
   VARCHAR
   YEAR DATA TYPE
​
root@(none):41: >help AUTO_INCREMENT
Name: 'AUTO_INCREMENT'
Description:
The AUTO_INCREMENT attribute can be used to generate a unique identity
for new rows:
​
URL: http://dev.mysql.com/doc/refman/8.0/en/example-auto-increment.html
​
Examples:
CREATE TABLE animals (
     id MEDIUMINT NOT NULL AUTO_INCREMENT,
     name CHAR(30) NOT NULL,
     PRIMARY KEY (id)
);
​
INSERT INTO animals (name) VALUES
    ('dog'),('cat'),('penguin'),
    ('lax'),('whale'),('ostrich');
​
SELECT * FROM animals;
​
root@(none):41: >help DATE
Name: 'DATE'
Description:
DATE
​
A date. The supported range is '1000-01-01' to '9999-12-31'. MySQL
displays DATE values in 'YYYY-MM-DD' format, but permits assignment of
values to DATE columns using either strings or numbers.
​
URL: http://dev.mysql.com/doc/refman/8.0/en/date-and-time-type-overview.html
​
​
root@(none):42: >help DATETIME
Name: 'DATETIME'
Description:
DATETIME[(fsp)]
​
A date and time combination. The supported range is '1000-01-01
00:00:00.000000' to '9999-12-31 23:59:59.999999'. MySQL displays
DATETIME values in 'YYYY-MM-DD HH:MM:SS[.fraction]' format, but permits
assignment of values to DATETIME columns using either strings or
numbers.
​
An optional fsp value in the range from 0 to 6 may be given to specify
fractional seconds precision. A value of 0 signifies that there is no
fractional part. If omitted, the default precision is 0.
​
Automatic initialization and updating to the current date and time for
DATETIME columns can be specified using DEFAULT and ON UPDATE column
definition clauses, as described in
http://dev.mysql.com/doc/refman/8.0/en/timestamp-initialization.html.
​
URL: http://dev.mysql.com/doc/refman/8.0/en/date-and-time-type-overview.html
​
​
root@(none):42: >help TIMESTAMP
Name: 'TIMESTAMP'
Description:
TIMESTAMP[(fsp)]
​
A timestamp. The range is '1970-01-01 00:00:01.000000' UTC to
'2038-01-19 03:14:07.999999' UTC. TIMESTAMP values are stored as the
number of seconds since the epoch ('1970-01-01 00:00:00' UTC). A
TIMESTAMP cannot represent the value '1970-01-01 00:00:00' because that
is equivalent to 0 seconds from the epoch and the value 0 is reserved
for representing '0000-00-00 00:00:00', the "zero" TIMESTAMP value.
​
An optional fsp value in the range from 0 to 6 may be given to specify
fractional seconds precision. A value of 0 signifies that there is no
fractional part. If omitted, the default precision is 0.
​
The way the server handles TIMESTAMP definitions depends on the value
of the explicit_defaults_for_timestamp system variable (see
http://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html).
​
If explicit_defaults_for_timestamp is enabled, there is no automatic
assignment of the DEFAULT CURRENT_TIMESTAMP or ON UPDATE
CURRENT_TIMESTAMP attributes to any TIMESTAMP column. They must be
included explicitly in the column definition. Also, any TIMESTAMP not
explicitly declared as NOT NULL permits NULL values.
​
If explicit_defaults_for_timestamp is disabled, the server handles
TIMESTAMP as follows:
​
Unless specified otherwise, the first TIMESTAMP column in a table is
defined to be automatically set to the date and time of the most recent
modification if not explicitly assigned a value. This makes TIMESTAMP
useful for recording the timestamp of an INSERT or UPDATE operation.
You can also set any TIMESTAMP column to the current date and time by
assigning it a NULL value, unless it has been defined with the NULL
attribute to permit NULL values.
​
Automatic initialization and updating to the current date and time can
be specified using DEFAULT CURRENT_TIMESTAMP and ON UPDATE
CURRENT_TIMESTAMP column definition clauses. By default, the first
TIMESTAMP column has these properties, as previously noted. However,
any TIMESTAMP column in a table can be defined to have these
properties.
​
URL: http://dev.mysql.com/doc/refman/8.0/en/date-and-time-type-overview.html
​
​
root@(none):42: >