mysql中的数据类型：
整数型：
#查看int整数型的帮助。
|
1
2
3
4
5
6
7
|
mysql> ? intName: '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
|
#查看创建数据库的帮助，这块发现使用schema不识别。
|
1
2
3
|
mysql> help create schemaNothing foundPlease try to run 'help contents' for a list of all accessible topics
|
#可以使用help ？ \h 三选一查看帮助。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
|
mysql> help create databaseName: '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 thisstatement, 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
|
|
1
2
3
4
5
6
7
|
mysql> ? tinyintName: 'TINYINT'
Description:TINYINT[(M)] [UNSIGNED] [ZEROFILL]A very small integer. The signed range is -128 to 127. The unsignedrange is 0 to 255.URL: http://dev.mysql.com/doc/refman/5.6/en/numeric-type-overview.html
|
|
1
2
3
4
5
6
7
|
mysql> \h intName: '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)
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
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)
|
#查看显示支持的存储引擎的信息：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
|
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)
|
本文转自青衫解衣 51CTO博客，原文链接:http://blog.51cto.com/215687833/1905770