The history of SQL-Structured Query Language

Source: Internet
Author: User

DDL: Data Manipulation language
INSERT
DELETE
SELECT
UPDATE
DML: Data Definition language
CREATE
DROP
Alter
DCL: Data Control Language
GRANT
REVOKE

Rdb object:
libraries, tables, indexes, views, users, stored procedures, stored functions, triggers, event schedulers.

    约束:    域约束:数据类型约束    外键约束:引用完整性约束    主键约束:某字段能唯一标识此字段所属的实体,并且不允许为空一张表中可以有多个    检查性约束:age:int

Relational database:
Presentation layer: Table
Logical layer: Storage engine
Physical Layer: Data file

数据存储和查询存储管理器:        权限机完整性管理        事务管理器        文件管理器        缓冲区管理器查询管理器:                DML解释器                DDL解释器                DCL解释器查询执行引擎mysql是单进程多线程的系统;不会给多个进程启动多个进程!线程复用mysql不支持对称多处理器(smp),意思是不能在一个sql处理分摊到多个cpu上处理,因此在处理速度上面就慢。

Relational operations:
Projection: Outputs only the specified fields
Select: Output only rows that match the criteria
Natural Links: Rows with the same value on all property values with the same name
Cartesian product:

SQL query statement:
Sequel---> SQL
SQL-86
SQL-89
SLQ-92
SQL-99
SQL-08

Part of the SQL language:
Ddl:
Dml:
Integrity Definition Language: Part of the DDL feature
View definition:
Transaction control:
Embedded SQL and dynamic sql:
Authorization: DCL

使用程序设计语言如何RDBMS交互:         嵌入式SQL:与动态SQL类似,但其语言必须程序编译时完全确定下来;         ODBC;针对的程序为 C         动态SQL:程序设计语言使用函数(mysql_conect())或者方法与RDBMS服务器建立连接,并进行交互;通过建立连接向SQL服务器发送查询语句,并将结果保存至变量中而后进行处理。        JDBC;针对的程序为 JAVAMYSQL支持插件式存储引擎mysql 5.5.8的之前的存储引擎是MyISAM,不支持事务。特别适合查询比较多但是修改比较少的场景。mysql 5.5.8版本之后的存储引擎是InnoDB,   表管理器:负责创建、读取或修改表定义文件;维护表描述高速缓存;管理表锁。表结构定义文件。表修改模块:表创建、删除、重命名、移除、更新或插入之类的操作表维护模块:;检查、修改、备份、恢复、优化(碎片整理)及解析;

Record organization in file:
Heap file organization: A record can be placed anywhere in the file.
Sequential file organization: According to the "Search code" value in order to store;
Hash file organization:

Table structure definition file; table data file
Tablespace: Table Space

The history of SQL-Structured Query Language

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