• 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: >

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  • 原文地址:https://www.cnblogs.com/plluoye/p/11182257.html
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