MySQL总结之SQL语句的应用

创建一个表：mysqlgt; CREATE TABLE students (-gt; sno CHAR(10) PRIMARY KEY,-gt; sname CHAR(8) NOT NULL,-gt; ssex CHAR

创建一个表：

mysql> CREATE TABLE students (

-> sno CHAR(10) PRIMARY KEY,

-> sname CHAR(8) NOT NULL,

-> ssex CHAR(1) NOT NULL CHECK(ssex = ‘F’ OR ssex = ‘M’),

-> sage INT NOT NULL,

-> sdept CHAR(20) DEFAULT ‘Computer’

-> )

-> ;

MySQl所支持的字符类型：

修改表结构：

mysql> ALTER TABLE students CHANGE sage sage INT UNSIGNED;

mysql> ALTER TABLE students ADD Grade1 INT NOT NULL DEFAULT ‘1’;

删除一个字段：

mysql> ALTER TABLE students DROP Grade1 ;

表重命名：

mysql> ALTER TABLE students RENAME students2;

数据库存储引擎类型：

存储引擎：相当于一个插件，，MySQL跟存储在磁盘上的文件进行交互的接口。

*************************** 1. row ***************************

Engine: InnoDB（行级别锁 粒度比较小）

Support: YES

Comment: Supports transactions, row-level locking, and foreign keys

Transactions: YES

XA: YES

Savepoints: YES

*************************** 2. row ***************************

Engine: MRG_MYISAM

Support: YES

Comment: Collection of identical MyISAM tables

Transactions: NO

XA: NO

Savepoints: NO

*************************** 3. row ***************************

Engine: BLACKHOLE

Support: YES

Comment: /dev/null storage engine (anything you write to it disappears)

Transactions: NO

XA: NO

Savepoints: NO

*************************** 4. row ***************************

Engine: CSV

Support: YES

Comment: CSV storage engine

Transactions: NO

XA: NO

Savepoints: NO

**********本文来源[email protected]搞@^&代*@码2网***************** 5. row ***************************

Engine: MEMORY

Support: YES

Comment: Hash based, stored in memory, useful for temporary tables

Transactions: NO

XA: NO

Savepoints: NO

*************************** 6. row ***************************

Engine: FEDERATED

Support: NO

Comment: Federated MySQL storage engine

Transactions: NULL

XA: NULL

Savepoints: NULL

*************************** 7. row ***************************

Engine: ARCHIVE

Support: YES

Comment: Archive storage engine

Transactions: NO

XA: NO

Savepoints: NO

*************************** 8. row ***************************

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