Written in front:

• The following are some of the statements that may need to be used in the work. Some of the statements that have been sorted out by various sorts are useful. If the query is incorrect, please switch to the user with DBA authority.
• These materials are shared with others for learning and use, and now I also organize and share them to implement our industry spirit.
• [I am a Java Web rookie programmer, if there is a mistake, please point out, lightly spray...]
• In the process of updating...

Oracle user tablespace creation

- For example, I want to create a user whose user is bidb. The password is bidb_123
create user bidb identified by bidb_123;

 - Grant bidb users various permissions
grant create session,create table,create view,create sequence,unlimited tablespace to bidb; 
grant create any procedure to bidb; 
grant execute any procedure to bidb;

 --Create a bidb tablespace
create tablespace bidb datafile '/u01/oracle/app/oradata/bidb/bidb_data01.dbf' size 1M autoextend on maxsize 30G extent management local;  
 --Extended table space
alter tablespace bidb add datafile '/u01/oracle/app/oradata/bidb/bidb_data02.dbf' size 1M autoextend on maxsize 30G;

 --Switch archive file
alter system switch logfile;

 --View database files
select * from dba_data_files;
 --View table space file size
select file_name,bytes/1024/1024 M from dba_data_files where tablespace_name='bidb';

 - Set the tablespace of the user bidb to bidb
alter user bidbdefault tablespace bidb;

 --delete users 
drop user bidb cascade;

 --Delete table space
drop tablespace bidb including contents and datafiles cascade constraint;

Oracle create dblink connection

- First create a dblink must have permission to create dblink
 -- Authorize the user bidb
grant create database link to bidb;

 - Create a dblink that can connect to the test user. The name of the dblink is defined here as testlink.
 --test_pwd: test user password Note the IP address, port number
create database link testlink
　　connect to test identified by test_pwd
　　using '(DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = orcl)
    )
  )';
  
 -- Once you've created it, you can use dblink, for example:
select * from t_test_user@testlink;

 -- If you want to create a public dblink, add /* public */ 
create  /* public */  database link ....
 --View dblink
select * from dba_db_links;
 --Delete dblink
drop public database link dblinkname;
drop /* public */ database link dblinkname;  

Modify the number of Oracle connections

--View how many times the Oracle database allows repeated connections by default. The default is 10 times.
select * from dba_profiles WHERE resource_name = 'FAILED_LOGIN_ATTEMPTS' AND PROFILE = 'DEFAULT';

 --Modify the default number of Oracle database connections to 100 users
alter profile default limit FAILED_LOGIN_ATTEMPTS 100;

 --Set unlimited
alter profile DEFAULT limit FAILED_LOGIN_ATTEMPTS UNLIMITED; 

Oracle user unlock statement

-- Unlock the user
ALTER USER username ACCOUNT UNLOCK;

Oracle query table space usage

select 
 B.file_id file ID number, 
 B.tablespace_name tablespace name, 
 B.bytes/1024/1024||'M' bytes, 
 (b.bytes-sum(nvl(a.bytes,0)))/1024/1024||'M' is used, 
 Sum(nvl(a.bytes,0))/1024/1024||'M' remaining space, 
 100 - sum(nvl(a.bytes,0))/(b.bytes)*100 Percentage of occupancy 
from dba_free_space a,dba_data_files b 
where a.file_id=b.file_id 
group by b.tablespace_name,b.file_id,b.bytes 
order by b.file_id;

View the current connection status of Oracle

  Select s.username username,
       S.osuser operating system user,
       S.program using the program,
       s.MACHINE server,
   s.sid,s.serial#,p.spid,
       'alter system kill session '||''''||trim(s.sid)||','||trim(s.serial#)||''';' Kill statement
   from v$session s,v$process p where s.paddr = p.addr 
       --and s.username =''; --Filter users

Query the sql statement that Oracle is executing

SELECT b.sid,  
               B.username username,
       b.serial#,
       spid,
       paddr,
               Sql_text is executing SQL,
               B.machine server,
               'alter system kill session ' || '''' || b.sid || ',' || b.serial# || '''' || ';' as kill statement
FROM v$process a, v$session b, v$sqlarea c 
WHERE a.addr = b.paddr AND b.sql_hash_value = c.hash_value 
 --and b.username=''; --Filter users

Query oracle currently locked object

SELECT l.session_id sid,  
       s.serial#,  
               L.locked_mode lock mode,  
               L.oracle_username username,  
               S.machine server,
               O.object_name is the name of the locked object,
               S.logon_time login database time,
               'alter system kill session ' || '''' || sid || ',' || s.serial# || '''' || ';' Kill statement
FROM v$locked_object l, all_objects o, v$session s 
WHERE l.object_id　= o.object_id 
AND l.session_id = s.sid; 

Kill can not handle the lock processing (ora-00031: session marked for kill)

If you use the above command to kill a process, the process state is set to "killed", but the locked resource has not been released for a long time, then you can kill the corresponding process (thread) at the os level, first execute the following The statement gets the process (thread) number:

select spid, osuser, s.program 
from v$session s,v$process p
 Where s.paddr=p.addr and s.sid=24; (24 is the sid above)

Kill this process (thread) on the OS:
1) On unix/linux, execute the command as root:

#kill -9 12345 (that is, the spid queried above)

2) In windows (unix also applies) kill the thread with orakill, orakill is an executable command provided by oracle, the syntax is:

orakill sid thread
 among them: 
 Sid: indicates the instance name to which the process to be killed belongs
 Thread: is the thread number to be killed, that is, the spid that is queried in step 3.
 Example: c:> orakill orcl 12345

PLSQL

Query data Chinese garbled solution

1. Execute the following statement

select (select value from nls_database_parameters where parameter = 'NLS_LANGUAGE') ||'_'||
(select value from nls_database_parameters where parameter = 'NLS_TERRITORY') ||'.'||
(select value from nls_database_parameters where parameter = 'NLS_CHARACTERSET') as NLS_LANG FROM DUAL;

2. Set environment variables

Set the NLS_LANG value obtained by the environment variable NLS_LANG to 1, and restart the PLSQL solution.

PLSQL solution & symbol insertion problem

Use the command line to execute set define off
Then continue to execute the statement you need to execute