Oracle entry command

Oracle entry command
Basic commands:
1. the spool command is used to screen recording in sqlplus.
Spool c: \ 1.txt automatically creates 1.txt, screen recording

Spool c: \ 1.txt append
Add to 1.txt

2. conn system/orcl switch user connection
3. -- meaning of the comment
4. exit
5. Clear screen: host cls;
6. Change the password:
// Change the password of the system user to system
Alter user system identified by system;
Alter user identified by is a keyword.

You can use
Sqlplus sys/aaa as sysdba; -- Log On as the database administrator.
You can enter the password at will.

7. Modify the SQL statement:
(1) run the c command
C/alert/alter (incorrect statement/pair Statement)
>/----/Run the previous command
User modified
(2) Modify through ed --- professional modification method
> Ed
Pop up Notepad to modify
8. Unlock: hr is the user name
Alter user hr account unlock;
9. show all display all commands
10. distinct is an important part of repeated rows.
11. set timing on; set the execution time
12. set timing off; time when the execution is canceled
13. set feedback off. When you cancel execution, the number of rows selected is displayed.
14. set feedback on; displays the number of rows selected during execution.
15. set heading off; cancel the header information of the field
16. set heading on; displays the header information of the field.
17. set trimout on;
18. set trimout off;

Ii. query table:
1. select * from tabs; query system table
2. select table_name from user_tables; Name of the table under the current user
3. desc table name query table structure
4. set linesize 120 to set the Row Height
5. col name for 9999 characters --- set the length of the stack bit
--- Col sal for 9999 (stack bit length)
6. The default length of set pagesize is 14.
7. set pagesize 0 indicates that there is no limit on the current display. pagination is prohibited.
8. show all to view some default oracle configurations
9. select * from tab to query all tables
10. select ename, job from emp; select the specified row
11. select sal * 12 from emp; operator operation
12. select sal * 12 + nvl (comm, 0) from emp; replace null with 0
13. filter conditions
-The use of the where clause, coupled with filtering conditions, must be followed by the from Table Name
SQL> -- where syntax select * | {distinct | express | clomn} from table name where filter Condition
Select * from emp where deptno = 20;
Select empno from emp where Deton = 20
Select * from emp where job = 'cler ';
Select * from emp where hiredate = '17-August-80'

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