数据库中的DML,DCL,DDL分别是那些操作?
来源:互联网 发布:xml与json的优缺点 编辑:程序博客网 时间:2024/04/30 16:13
原文出处:http://liyuan2005.iteye.com/blog/209218
数据库中的DML,DCL,DDL分别是那些操作?
DDL
Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:
CREATE - to create objects in the database
ALTER - alters the structure of the database
DROP - delete objects from the database
TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
COMMENT - add comments to the data dictionary
RENAME - rename an object
DML
Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:
SELECT - retrieve data from the a database
INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - deletes all records from a table, the space for the records remain
MERGE - UPSERT operation (insert or update)
CALL - call a PL/SQL or Java subprogram
EXPLAIN PLAN - explain access path to data
LOCK TABLE - control concurrency
DCL
Data Control Language (DCL) statements. Some examples:
GRANT - gives user's access privileges to database
REVOKE - withdraw access privileges given with the GRANT command
TCL
Transaction Control (TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions.
COMMIT - save work done
SAVEPOINT - identify a point in a transaction to which you can later roll back
ROLLBACK - restore database to original since the last COMMIT
SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML,DCL,DDL分别是那些操作?
- 数据库中的DML、DDL、DCL区别
- 数据库: DML、DDL、DCL
- 数据库 DDL","DML","DCL"
- SQL中的DML,DDL,DCL分别表示的是什么
- 数据库DDL、DML和DCL
- 数据库DDL,DML,DCL,TCL
- 数据库DML、DDL、DCL区别
- DML、DDL、DCL三者定义(数据库的操作)
- 数据库操作语句类型(DQL、DML、DDL、DCL)简介
- 数据库操作语句类型(DQL、DML、DDL、DCL)简介
- Informix索引性能调优的建议
- 实现执行scp命令时不需要输入用户密码
- 为什么联合抵制苹果的运动总是失败?
- mysql动态分页存储过程
- java取整和java四舍五入方法 BigDecimal.setScale()方法详解.
- 数据库中的DML,DCL,DDL分别是那些操作?
- 关于ios中时间差的计算
- 去除 Cygwin 编译的程序对Cygwin1.dll的依赖
- 删除重复记录的方法
- Adobe驳Flash消亡论:重点放在页游开发
- 魔鬼车间
- iPhone入门 - UIAlertView用法
- UBUNTU添加开机自动启动程序方法
- windows server 2008 r2密码