What are the basic statements of Oracle database?

Oracle database basic statements: 1. Create database; 2. Delete database; 3. Back up database; 4. Database restore; 5. Rename table; 6. Modify fields; 7. Delete index, etc.

The operating environment of this tutorial: Windows 7 system, Oracle version, DELL G3 computer.

Basic statements of oracle database:

1. Oracle database operation

1. Create database

create database databasename

2. Delete database

drop database dbname

3. Back up database

Full backup

exp demo/demo@orcl buffer=1024 file=d：back.dmp full=y

• demo: username, password

• buffer: cache size

• file: specific backup file address

• full: whether to export all files

• ignore: Ignore the error. If the table already exists, it will also be overwritten.

Export the tables of the system user and sys user in the database

exp demo/demo@orcl file=d:backup1.dmp owner=(system,sys)

Export the specified table

exp demo/demo@orcl file=d:backup2.dmp tables=(teachers,students)

According to the filter conditions, export

exp demo/demo@orcl file=d：back.dmp tables=（table1） query=" where filed1 like 'fg%'"

Compression can be performed when exporting; add compress=y after the command; if logs are needed, follow: log=d:log. txt

Back up the database of the remote server

exp username/password@remote IP:port/instance file=storage location:file name.dmp full=y

4. Database restoration

Open cmd and directly execute the following command without logging in to sqlplus.

Complete Restore

imp demo/demo@orcl file=d:back.dmp full=y ignore=y log=D:implog.txt

It is important to specify the log to facilitate error analysis and remediation.

Import the specified table

imp demo/demo@orcl file=d:backup2.dmp tables=(teachers,students)

Restore to the remote server

imp username/password@remote IP:port/instance file=storage location: file name.dmp full =y

2. Oracle table operations

1. Create table

create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)

Create a new table based on the existing table:

A:

select * into table_new from table_old (使用旧表创建新表)

B:

create table tab_new as select col1,col2… from tab_old definition only<仅适用于Oracle>

2. Delete table

drop table tabname

3. Rename table

Description: alter table table name rename to new Table name

eg:

alter table tablename rename to newtablename

4. Add fields

Description: alter table table name add (field name field type default value is empty);

Example:

alter table tablename add (ID int);

alter table tablename add (ID varchar2(30) default '空' not null);

5. Modify fields

Description: alter table table name modify (field name field type default value is empty);

eg:

alter table tablename modify (ID number(4));

6. Duplicate name fields

Description: alter table table name rename column column name to new column name (where: column is the keyword)

eg:

alter table tablename rename column ID to newID;

7. Delete fields

Instructions: alter table table name drop column field name;

eg:

alter table tablename drop column ID;

8.Add primary key

alter table tabname add primary key(col)

9. Delete the primary key

alter table tabname drop primary key(col)

10. Create an index

create [unique] index idxname on tabname(col….)

11. Delete the index

drop index idxname

Note: The index cannot be changed. If you want to change it, you must delete it and rebuild it.

12. Create a view

create view viewname as select statement

13. Delete a view

drop view viewname

3. Oracle operation data

1. Data query

select <列名> from <表名> [where <查询条件表达试>] [order by <排序的列名>[asc或desc]]

2. Insert data

insert into 表名 values(所有列的值);
insert into test values(1,'zhangsan',20);

insert into 表名(列) values(对应的值);
insert into test(id,name) values(2,'lisi');

3. Update data

update 表 set 列=新的值 [where 条件] -->更新满足条件的记录
update test set name='zhangsan2' where name='zhangsan'

update 表 set 列=新的值 -->更新所有的数据
update test set age =20;

4. Delete data

delete from 表名 where 条件 -->删除满足条件的记录
delete from test where id = 1;

• delete from test -- >Delete all

• commit; -->Commit data

• rollback; -->Rollback data

The delete method can recover the deleted data, but once it is submitted, there is no way. When delete is deleted, a log will be recorded -->The deletion will be very slow.

truncate table 表名

Delete all Data will not affect the table structure, logs will not be recorded, and the data cannot be restored -->Delete quickly

drop table 表名

Delete all data, including the table structure, no logs will be recorded, and the data cannot be restored- ->Delete quickly

5. Data copy

Table data copy

insert into table1 (select * from table2);

Copy table structure

create table table1 select * from table2 where 1>1;

Copy table structure and data

create table table1 select * from table2;

Copy specified fields

create table table1 as select id, name from table2 where 1>1;

4. Database copy command

Recommended (free) ：oracle

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