DDL, DML不是所有SQL都是可以自动回滚的
因为DDL没有事务性,所以DDL不能回滚。
要实现自动回滚。(begin,commit,rollback),则SQL语句中只能包括DML。
这样,自动化发布就会受限规范格式。
故而,一刀切的办法是,假定所有SQL不支持事务,自已定义好ROLLBACK的SQL脚本,在出错时能用代码回滚,
而不是依赖于数据库本身的功能。
========================
DDL和DML
DDL (Data Definition Language 数据定义语言)
create table 创建表
alter table 修改表
drop table 删除表
truncate table 删除表中所有行
create index 创建索引
drop index 删除索引
当执行DDL语句时,在每一条语句前后,oracle都将提交当前的事务。如果用户使用insert命令将记录插入到数据库后,执行了一条DDL语句(如create table),此时来自insert命令的数据将被提交到数据库。当DDL语句执行完成时,DDL语句会被自动提交,不能回滚。
DML (Data Manipulation Language 数据操作语言)
insert 将记录插入到数据库
update 修改数据库的记录
delete 删除数据库的记录
当执行DML命令如果没有提交,将不会被其他会话看到。除非在DML命令之后执行了DDL命令或DCL命令,或用户退出会话,或终止实例,此时系统会自动发出commit命令,使未提交的DML命令提交。
Table 14.8 Online DDL Support for Index Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Creating or adding a secondary index | Yes | No | Yes | No |
Dropping an index | Yes | No | Yes | Yes |
Adding a | Yes* | No* | No | No |
Table 14.9 Online DDL Support for Primary Key Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a primary key | Yes* | Yes* | Yes | No |
Dropping a primary key | No | Yes | No | No |
Dropping a primary key and adding another | Yes | Yes | Yes | No |
Table 14.10 Online DDL Support for Column Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a column | Yes | Yes | Yes* | No |
Dropping a column | Yes | Yes | Yes | No |
Renaming a column | Yes | No | Yes* | Yes |
Reordering columns | Yes | Yes | Yes | No |
Setting a column default value | Yes | No | Yes | Yes |
Changing the column data type | No | Yes | No | No |
Dropping the column default value | Yes | No | Yes | Yes |
Changing the auto-increment value | Yes | No | Yes | No* |
Making a column | Yes | Yes* | Yes | No |
Making a column | Yes* | Yes* | Yes | No |
Table 14.11 Online DDL Support for Foreign Key Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a foreign key constraint | Yes* | No | Yes | Yes |
Dropping a foreign key constraint | Yes | No | Yes | Yes |
Table 14.12 Online DDL Support for Table Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Changing the | Yes | Yes | Yes | No |
Changing the | Yes | Yes | Yes | No |
Setting persistent table statistics | Yes | No | Yes | Yes |
Specifying a character set | Yes* | Yes* | No | No |
Converting a character set | No | Yes | No | No |
Optimizing a table | Yes* | Yes | Yes | No |
Rebuilding with the | Yes* | Yes | Yes | No |
Performing a null rebuild | Yes* | Yes | Yes | No |
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用以致学,学以致用
因为DDL没有事务性,所以DDL不能回滚。
要实现自动回滚。(begin,commit,rollback),则SQL语句中只能包括DML。
这样,自动化发布就会受限规范格式。
故而,一刀切的办法是,假定所有SQL不支持事务,自已定义好ROLLBACK的SQL脚本,在出错时能用代码回滚,
而不是依赖于数据库本身的功能。
========================
DDL和DML
DDL (Data Definition Language 数据定义语言)
create table 创建表
alter table 修改表
drop table 删除表
truncate table 删除表中所有行
create index 创建索引
drop index 删除索引
当执行DDL语句时,在每一条语句前后,oracle都将提交当前的事务。如果用户使用insert命令将记录插入到数据库后,执行了一条DDL语句(如create table),此时来自insert命令的数据将被提交到数据库。当DDL语句执行完成时,DDL语句会被自动提交,不能回滚。
DML (Data Manipulation Language 数据操作语言)
insert 将记录插入到数据库
update 修改数据库的记录
delete 删除数据库的记录
当执行DML命令如果没有提交,将不会被其他会话看到。除非在DML命令之后执行了DDL命令或DCL命令,或用户退出会话,或终止实例,此时系统会自动发出commit命令,使未提交的DML命令提交。
Table 14.8 Online DDL Support for Index Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Creating or adding a secondary index | Yes | No | Yes | No |
Dropping an index | Yes | No | Yes | Yes |
Adding a | Yes* | No* | No | No |
Table 14.9 Online DDL Support for Primary Key Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a primary key | Yes* | Yes* | Yes | No |
Dropping a primary key | No | Yes | No | No |
Dropping a primary key and adding another | Yes | Yes | Yes | No |
Table 14.10 Online DDL Support for Column Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a column | Yes | Yes | Yes* | No |
Dropping a column | Yes | Yes | Yes | No |
Renaming a column | Yes | No | Yes* | Yes |
Reordering columns | Yes | Yes | Yes | No |
Setting a column default value | Yes | No | Yes | Yes |
Changing the column data type | No | Yes | No | No |
Dropping the column default value | Yes | No | Yes | Yes |
Changing the auto-increment value | Yes | No | Yes | No* |
Making a column | Yes | Yes* | Yes | No |
Making a column | Yes* | Yes* | Yes | No |
Table 14.11 Online DDL Support for Foreign Key Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Adding a foreign key constraint | Yes* | No | Yes | Yes |
Dropping a foreign key constraint | Yes | No | Yes | Yes |
Table 14.12 Online DDL Support for Table Operations
Operation | In Place | Rebuilds Table | Permits Concurrent DML | Only Modifies Metadata |
Changing the | Yes | Yes | Yes | No |
Changing the | Yes | Yes | Yes | No |
Setting persistent table statistics | Yes | No | Yes | Yes |
Specifying a character set | Yes* | Yes* | No | No |
Converting a character set | No | Yes | No | No |
Optimizing a table | Yes* | Yes | Yes | No |
Rebuilding with the | Yes* | Yes | Yes | No |
Performing a null rebuild | Yes* | Yes | Yes | No |