mysql中的数据类型：
整数型：
#查看int整数型的帮助。
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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
.6
/en/numeric-type-overview
.html
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#查看创建数据库的帮助，这块发现使用schema不识别。
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mysql> help create schema
Nothing found
Please try to run
'help contents'
for
a list of all accessible topics
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#可以使用help ？ \h 三选一查看帮助。
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mysql> help create database
Name:
'CREATE DATABASE'
Description:
Syntax:
CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
[create_specification] ...
create_specification:
[DEFAULT] CHARACTER SET [=] charset_name
| [DEFAULT] COLLATE [=] collation_name
CREATE DATABASE creates a database with the given name. To use this
statement, you need the CREATE privilege
for
the database. CREATE
SCHEMA is a synonym
for
CREATE DATABASE.
URL: http:
//dev
.mysql.com
/doc/refman/5
.6
/en/create-database
.html
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mysql> ? tinyint
Name:
'TINYINT'
Description:
TINYINT[(M)] [UNSIGNED] [ZEROFILL]
A very small integer. The signed range is -128 to 127. The unsigned
range is 0 to 255.
URL: http:
//dev
.mysql.com
/doc/refman/5
.6
/en/numeric-type-overview
.html
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mysql> \h 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
.6
/en/numeric-type-overview
.html
|
浮点类型：
M是数字总位数，D是小数点后面的位数。
float(M,D)
字符串类型：
char(M) M个字节，0-255
varchar(M) L+1个字节，0-65535
日期时间类型：
time
date
datetime
year
#查看mysql有那些存储引擎(默认是innodb)
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mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| MEMORY | YES | Hash based, stored
in
memory, useful
for
temporary tables | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| BLACKHOLE | YES |
/dev/null
storage engine (anything you write to it disappears) | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows
in
set
(0.00 sec)
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#查看显示支持的存储引擎的信息：
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mysql> show variables like
'have%'
;
+----------------------+----------+
| Variable_name | Value |
+----------------------+----------+
| have_compress | YES |
| have_crypt | YES |
| have_dynamic_loading | YES |
| have_geometry | YES |
| have_openssl | DISABLED |
| have_profiling | YES |
| have_query_cache | YES |
| have_rtree_keys | YES |
| have_ssl | DISABLED |
| have_symlink | DISABLED |
+----------------------+----------+
10 rows
in
set
(0.00 sec)
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本文转自青衫解衣 51CTO博客，原文链接:http://blog.51cto.com/215687833/1905770
