高效查看MySQL幫助文檔的方法

在mysql的使用過程中, 可能經常會遇到以下問題:

• 某個操作語法忘記了, 如何快速查找?
• 如何快速知道當前版本上某個字段類型的取值范圍?
• 當前版本都支持哪些函數?希望有例子說明..
• 當前版本是否支持某個功能?

    對於上面列出的問題, 我們可能想到的方法是查找MySQL的文檔, 這些問題在官方文檔都可以很清楚地查到, 但是卻要耗費大量的時間和精力.

    所以對於以上問題, 最好的解決辦法就是使用MySQL安裝后自帶的幫助文檔, 這樣在遇到問題時就可以方便快捷地進行查詢.

 

 

按層次查看幫助

查看目錄    

如果不知道幫助能夠提供些什么, 可以用"? contents"命令來顯示所有可供查詢的分類, 如下例所示:

mysql> ? 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
   Procedures
   Storage Engines
   Table Maintenance
   Transactions
   User-Defined Functions
   Utility

查看數據類型

對於列出的分類, 可以使用"? 類別名稱"的方式針對用戶感興趣的內容做進一步的查看, 例如, 想看看MySQL都支持哪些數據類型, 可以執行"? data tyeps"命令:

mysql> ? 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

上面列出了此版本支持的所有數據類型, 如果想知道int類型的具體介紹, 也可以利用上面的方法, 做進一步的查看:

mysql> ? int
Name: 'INT'
Description:
INT[(M)] [UNSIGNED] [ZEROFILL]
A normal-size integer. The signed range is -2147483648 to 2147483647.
The unsigned range is 0 to 4294967295.
URL: http://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html

查看函數

mysql> ? functions
You asked for help about help category: "Functions"
For more information, type 'help <item>', where <item> is one of the following
categories:
   Bit Functions
   Comparison operators
   Control flow functions
   Date and Time Functions
   Encryption Functions
   Information Functions
   Logical operators
   Miscellaneous Functions
   Numeric Functions
   String Functions

再根據列出的目錄查看相應函數,比如查看都有什么日期函數

mysql> ? Date and Time Functions
You asked for help about help category: "Date and Time Functions"
For more information, type 'help <item>', where <item> is one of the following
topics:
   ADDDATE
   ADDTIME
   CONVERT_TZ
   CURDATE
   CURRENT_DATE
   CURRENT_TIME
   CURRENT_TIMESTAMP
   CURTIME
   DATE FUNCTION
   DATEDIFF
   DATE_ADD
   DATE_FORMAT
   DATE_SUB
   DAY
   DAYNAME
   DAYOFMONTH
   DAYOFWEEK
   DAYOFYEAR
   EXTRACT
   FROM_DAYS
   FROM_UNIXTIME
   GET_FORMAT
   HOUR
   LAST_DAY
   LOCALTIME
   LOCALTIMESTAMP
   MAKEDATE
   MAKETIME
   MICROSECOND
   MINUTE
   MONTH
   MONTHNAME
   NOW
   PERIOD_ADD
   PERIOD_DIFF
   QUARTER
   SECOND
   SEC_TO_TIME
   STR_TO_DATE
   SUBDATE
   SUBTIME
   SYSDATE
   TIME FUNCTION
   TIMEDIFF
   TIMESTAMP FUNCTION
   TIMESTAMPADD
   TIMESTAMPDIFF
   TIME_FORMAT
   TIME_TO_SEC
   TO_DAYS
   TO_SECONDS
   UNIX_TIMESTAMP
   UTC_DATE
   UTC_TIME
   UTC_TIMESTAMP
   WEEK
   WEEKDAY
   WEEKOFYEAR
   YEAR
   YEARWEEK

 

快速查閱幫助

    在實際應用當中, 如果需要快速查閱某項語法時, 可以使用關鍵字進行快速查詢. 例如, 想知道show命令都能看到什么東西, 可以用如下命令:

mysql> ? show
Name: 'SHOW'
Description:
SHOW has many forms that provide information about databases, tables,
columns, or status information about the server. This section describes
those following:
SHOW AUTHORS
SHOW {BINARY | MASTER} LOGS
SHOW BINLOG EVENTS [IN 'log_name'] [FROM pos] [LIMIT [offset,] row_count]
SHOW CHARACTER SET [like_or_where]
SHOW COLLATION [like_or_where]
SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [like_or_where]
SHOW CONTRIBUTORS
SHOW CREATE DATABASE db_name
SHOW CREATE EVENT event_name
SHOW CREATE FUNCTION func_name
SHOW CREATE PROCEDURE proc_name
SHOW CREATE TABLE tbl_name
SHOW CREATE TRIGGER trigger_name
SHOW CREATE VIEW view_name
SHOW DATABASES [like_or_where]
SHOW ENGINE engine_name {STATUS | MUTEX}
SHOW [STORAGE] ENGINES
SHOW ERRORS [LIMIT [offset,] row_count]
SHOW EVENTS
SHOW FUNCTION CODE func_name
SHOW FUNCTION STATUS [like_or_where]
SHOW GRANTS FOR user
SHOW INDEX FROM tbl_name [FROM db_name]
SHOW MASTER STATUS
SHOW OPEN TABLES [FROM db_name] [like_or_where]
SHOW PLUGINS
SHOW PROCEDURE CODE proc_name
SHOW PROCEDURE STATUS [like_or_where]
SHOW PRIVILEGES
SHOW [FULL] PROCESSLIST
SHOW PROFILE [types] [FOR QUERY n] [OFFSET n] [LIMIT n]
SHOW PROFILES
SHOW SLAVE HOSTS
SHOW SLAVE STATUS
SHOW [GLOBAL | SESSION] STATUS [like_or_where]
SHOW TABLE STATUS [FROM db_name] [like_or_where]
SHOW [FULL] TABLES [FROM db_name] [like_or_where]
SHOW TRIGGERS [FROM db_name] [like_or_where]
SHOW [GLOBAL | SESSION] VARIABLES [like_or_where]
SHOW WARNINGS [LIMIT [offset,] row_count]
like_or_where:
    LIKE 'pattern'
  | WHERE expr
If the syntax for a given SHOW statement includes a LIKE 'pattern'
part, 'pattern' is a string that can contain the SQL "%" and "_"
wildcard characters. The pattern is useful for restricting statement
output to matching values.
Several SHOW statements also accept a WHERE clause that provides more
flexibility in specifying which rows to display. See
http://dev.mysql.com/doc/refman/5.5/en/extended-show.html.
URL: http://dev.mysql.com/doc/refman/5.5/en/show.html

例如, 想查看某個函數CONCAT的使用

mysql> ? concat
Name: 'CONCAT'
Description:
Syntax:
CONCAT(str1,str2,...)
Returns the string that results from concatenating the arguments. May
have one or more arguments. If all arguments are nonbinary strings, the
result is a nonbinary string. If the arguments include any binary
strings, the result is a binary string. A numeric argument is converted
to its equivalent string form. This is a nonbinary string as of MySQL
5.5.3. Before 5.5.3, it is a binary string; to to avoid that and
produce a nonbinary string, you can use an explicit type cast, as in
this example:
SELECT CONCAT(CAST(int_col AS CHAR), char_col);
CONCAT() returns NULL if any argument is NULL.
URL: http://dev.mysql.com/doc/refman/5.5/en/string-functions.html
Examples:
mysql> SELECT CONCAT('My', 'S', 'QL');
        -> 'MySQL'
mysql> SELECT CONCAT('My', NULL, 'QL');
        -> NULL
mysql> SELECT CONCAT(14.3);
        -> '14.3'

又例如, 如果想查看create table的語法, 可以使用以下命令:

mysql> ? create table
Name: 'CREATE TABLE'
Description:
Syntax:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    (create_definition,...)
    [table_options]
    [partition_options]
Or:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    [(create_definition,...)]
    [table_options]
    [partition_options]
    select_statement
Or:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    { LIKE old_tbl_name | (LIKE old_tbl_name) }
    ......

再舉一個例子吧, 比如想查看創建用戶GRANT語法怎么寫

mysql> ? grant
Name: 'GRANT'
Description:
Syntax:
GRANT
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    TO user_specification [, user_specification] ...
    [REQUIRE {NONE | ssl_option [[AND] ssl_option] ...}]
    [WITH with_option ...]
GRANT PROXY ON user_specification
    TO user_specification [, user_specification] ...
    [WITH GRANT OPTION]
object_type:
    TABLE
  | FUNCTION
  | PROCEDURE
      ......

下面把查看手冊和官方資料的地址獻上, 就把衣缽都傳給你們了, 別忘了給個贊哦~

 

常用的網絡資源

http://dev.mysql.com/downloads/是MySQL的官方網站, 可以下載到各個版本的MySQL以及相關客戶端開發工具等.

http://dev.mysql.com/doc/提供了目前最權威的MySQL數據庫及工具的在線手冊

http://bugs.mysql.com/ 這里可以查看到MySQL已經發布的bug列表, 或者向MySQL提交bug報告

http://www.mysql.com/news-and-events/newsletter/通常會發布各種關於MySQL的最新消息.