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 u01mytmpmysql.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 andor its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation andor 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 .
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 multibyte 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 UserDefined 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: 20190220
root@(none):39: >help HELP_VERSION
Name: 'HELP_VERSION'
Description:
This help information was generated from the MySQL 8.0 Reference Manual
on: 20190220 (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 '10000101' to '99991231'. MySQL
displays DATE values in 'YYYYMMDD' 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 '10000101
00:00:00.000000' to '99991231 23:59:59.999999'. MySQL displays
DATETIME values in 'YYYYMMDD 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 '19700101 00:00:01.000000' UTC to
'20380119 03:14:07.999999' UTC. TIMESTAMP values are stored as the
number of seconds since the epoch ('19700101 00:00:00' UTC). A
TIMESTAMP cannot represent the value '19700101 00:00:00' because that
is equivalent to 0 seconds from the epoch and the value 0 is reserved
for representing '00000000 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: >