安装了mysql-refman-5.-en-html-chapter-1-.noarch.rpm，从哪里打开？
rpm -iv mysql-refman-5.-en-html-chapter-1-.noarch.rpm
安装后，从哪里打开这帮助手册。

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直接从网上下载一个看啊
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mysql> help contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the following
categories:
Account Management
Administration
Compound Statements
Data Definition
Data Manipulation
Data Types
Functions
Functions and Modifiers for Use with GROUP BY
Geographic Features
Help Metadata
Language Structure
Plugins
Table Maintenance
Transactions
User-Defined Functions
Utility

mysql> 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

mysql> help TIME
Name: 'TIME'
Description:
TIME

A time. The range is '-838:59:59' to '838:59:59'. MySQL displays TIME
values in 'HH:MM:SS' format, but permits assignment of values to TIME
columns using either strings or numbers.

URL: http://dev.mysql.com/doc/refman/5.5/en/date-and-time-type-overview.html

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man mysql