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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